Yesterday I pointed out the three most important reasons, at least in my mind, why B2B is going to be an enduringly important part of American business and represents a great investment opportunity.

Because it's a

structural

change in how big companies do business, because the deals are large, and because B2B is a key step in delivering ever-shorter-cycle business processes, B2B is an idea whose time has come. And it's going to be a rich field.

As I said in

yesterday's column, my friend and colleague

Adam Lashinsky

doubts the import of B2B, and has repeatedly called it a "craze" and a "mania." I certainly agree that some B2B stocks have been bid up to ridiculous levels. But taking a long-term view, I think reverse-auction market-maker plays such as

VerticalNet

(VERT)

,

Internet Capital Group

(ICGE)

,

CommerceOne

(CMRC)

TheStreet Recommends

and particularly

Ariba

(ARBA)

may well prove to be undervalued today.

That's tough to say with these stocks trading at soaring multiples. But consider: Ariba has slipped from 320 to 260, VerticalNet from 250 to 200, ICGE from 200 to 110, and CommerceOne from 260 to around 200, since earlier this year.

Can you say "buying opportunity?" Are all three multiples still too high, still too scary?

Despite my enthusiasm for the B2B model, the road ahead is hardly a smooth one. I have three worries about the future of B2B stocks:

    Changes in the Revenue Model: I have sat through so many of these B2B companies' pitches that were cut from the same cloth that I've begun to wonder if there's a Web site somewhere selling canned pitch scripts for B2B execs. Talk about a template view of reality! How will they make money? "Well, of course we have many revenue opportunities with our business model, but the big win is going to come from taking just a tiny slice of each transaction. Even if it's only one-half percent of the total sale, these are big deals and we're going to be doing a lot of them, so that will add up fast! And sotto voce we think we may be able to get that number up to 3%, maybe 4%, even 5% in some of our deals. Sweet, huh?" Talk about vigorish -- you bet, give me a little slice off the top of a lot of fat deals, and I'll make a bundle, too. But it may not work that way. The biggest companies -- the ones the B2B crowd most wants to sign up -- are smarter than your average bear, and they have plenty of capital. They're starting to resist mightily this pitch to bring a B2B market maker under the tent as a partner rather than as a supplier, saying, in effect, "Just sell us the software, thanks. A one-time item plus some ongoing charges for support and upgrades. No cut of every deal, thanks; we're smarter than that." In one of the most high-profile cases of these maybe-not-the-way-it-was-supposed-to-be deals, Ariba announced in February that it had signed up Philip Morris' (MO) - Get ReportKraft Foods division as a client/partner, using Ariba's excellent B2B software. But it's been widely rumored that this wasn't your basic "transaction-based revenue model" deal. Rather, Kraft supposedly just licensed the software, with no shares of each transaction going to Ariba. Whether those rumors about the Ariba-Kraft deal prove true or not -- I can't get anyone to talk about it on the record -- if a trend of clients declining revenue-sharing deals gets established, it severely compromises the revenue models and business plans of many B2B providers. It's awfully early in the lives of these companies to have to rewrite their business plans to accommodate such a fundamental change. Access to Capital: The impact of the Barron's story last weekend on possible coming difficulties in access to capital for dot-coms continues to ripple through the market. Yes, the story overstated the problem somewhat; no, it wasn't wrongheaded. In general, I think the best and biggest B2Bs have enough momentum that access to the additional capital needed to build their markets won't be impossible. But the teller's window won't stay open forever. Pricing on convertible deals continues to rise, and an unacceptably high cost of capital will mean no access to capital for many companies. Selling customers on the idea of moving to a B2B reverse-auction site for their purchasing, then actually building those sites, is a surprisingly expensive proposition. You get the advantages of reusable technology, but the sale can be a surprisingly tough one. And the B2B outfits are going up against potential customers who know how to make deals. In other words, as much as International Bubba may want to do a deal with a B2B market maker, it knows how to play its cards close to the vest, and how to drive the B2B supplier up against the wall on price. Confusion and Conflict: If my company is interested in moving to a B2B purchasing model, do I want to set up my own little closed market fair, through which my suppliers will bid their way down on my specific purchase orders? Or do I want to go to a broader marketplace constructed by a vertical B2B market maker, where many buyers compete with many other buyers to purchase items from many suppliers? It's not an academic question. We'll see -- we already see -- examples of both. The Big Three automakers' joint B2B deal, for example, will certainly attract all the potential suppliers they could possibly want -- and the automakers have the clout to make it work. Other "industry-verticals," such as those being set up by VerticalNet, will allow all of the players on both sides in specific industries to meet in an online bazaar and cut deals. But for those just coming to the table, it can be confusing to decide which path to follow. The noise in this marketplace is deafening, and B2B salespeople's "overclaim" isn't making it any quieter, easier or more certain. When people face confusion and chaos, they often retreat, making no decision at all. If the B2B market stays as confusing for newcomers on both sides of the buying table as it is today, it could retard the growth of this marketplace, and damage the reputations of the major market makers.

B2B's a strong play. There are good investments out there, especially after the battering B2Bs and tech generally have taken over the past several weeks. The above three pitfalls notwithstanding, the arguments I set out

yesterday combine to persuade me B2B's going to be a big success, and change how many companies do business.

That's the kind of action I want as an investor.

Jim Seymour is president of Seymour Group, an information-strategies consulting firm working with corporate clients in the U.S., Europe and Asia, and a longtime columnist for PC Magazine. Under no circumstances does the information in this column represent a recommendation to buy or sell stocks. At time of publication, Seymour was long Internet Capital Group, although holdings can change at any time. Seymour does not write about companies that are current or recent consulting clients of Seymour Group. While Seymour cannot provide investment advice or recommendations, he invites your feedback at

jseymour@thestreet.com.