Highly doubt Apple is going to use the same pricing model as Snow Leopard. Apple acknowledged that Snow Leopard wasn't a "new" OS, instead it was mostly an extension of Leopard. From the keynote, it looks like Apple is suggesting that Lion is a whole new OS, with the "Back to Mac" line - bringing iOS features to OS X. For me, I think a reasonable price that won't really anger users would be $99 but even at that price, it wouldn't be a definite buy for me just based on what's been previewed so far.