Updated from 10:40 a.m. EDTDeal speculation thrives in a vacuum. Amid unconfirmed rumors of merger talks between IBM ( IBM) and Sun Micro ( JAVA), investors are mulling three major concerns about the stocks: price, regulatory review and product shelf life. The price of the deal seems to be the biggest hang-up and the most crucial element for an investment community trying to gauge the premium IBM will agree to pay for Sun. When The Wall Street Journal first reported the deal discussions last week, the preliminary terms called for IBM to pay $10 to $11 a share, or a total of $6.5 billion, for Sun. The price tag represented a 100% premium and immediately sparked questions about whether IBM was overpaying for a setting Sun. Since then, some buy-side analysts, who have been probing the issue, say the price is likely to be closer to the $8- to $9-a-share range than the original $10 to $11 figure. These people say they still remain encouraged that terms will eventually be reached.