NEW YORK ( TheStreet) -- The price of natural gas has collapsed, falling from more than $13 per million British thermal units in 2008 to $3.43 now. The decline sliced the profit margins of gas producers and caused the stocks to languish.Now some managers of value mutual funds have become intrigued. Funds that have been buying gas shares include Croft Value ( CLVFX) and Schwartz Value ( RCMFX). The bulls say that gas prices have started to rise in recent months and more gains are likely. But even the optimists concede that it will take time for prices to recover fully. "I don't know what prices will be in one year, but five years from now we will be happy that we bought these stocks," says Kent Croft, portfolio manager of Croft Value. Don't expect to see a crowd of funds rushing to the gas stocks any time soon. Not many fund managers are willing to wait several years for stocks to climb. But Croft is unusually patient, keeping his average holding for more than five years. The low-turnover strategy has worked. During the past ten years, the fund has returned 9.1% annually, outdoing 96% of large blend funds, according to Morningstar. The gas stocks suit Croft's taste because the industry's long-term future looks so much brighter than the present situation. He says that gas prices sank because of dramatic shifts in supply and demand. During the financial crisis, demand sank as manufacturers and utilities burned less gas. At the same time, supplies spurted as new fracking technologies enabled producers to deliver more gas. Croft says demand will grow substantially in coming years. Because gas causes less pollution and is cheaper than oil, chemical manufacturers are building new gas-fired plants. Power companies are shifting from coal to gas. Gas could also become more popular as cheap fuel for vehicles. Already 15% of the country's municipal fleets of buses and trash collection trucks have engines that can run on gas. Commercial vehicles have been slow to shift because few service stations provide natural gas. But now several gas companies have decided to invest hundreds of millions of dollars to provide natural gas fuel stations at truck stops.