Is the unlocked phone even available at the apple stores?
In the United States, no, Apple Stores do not have an unlocked iPhone.
However, they
do have non-contract prices for iPhones. They're still locked to AT&T, so you still cannot use them with another carrier unless you hack them. But they do not require a 2-year commitment.
(Overall, it actually works out to be cheaper to purchase the iPhone at the subsidized price, pay for the first month's service, then pay the ETF to terminate the contract at the end of the first month. After that point, you'd end up with a phone with the exact same status as you would have had with the no-commitment price iPhone, but you'll have spent about $100 less.)
In Canada, on the other hand, there are no-contract prices available for the 8 GB iPhone 3G, and for the iPhone 3GS. But the only option to buy the 16 GB iPhone 3G is to commit to a 3-year contract.
(ETFs in Canada from Rogers and Fido are substantially higher than in the USA from AT&T, so the argument above about the pros and cons of the no-commitment pricing versus subsidized-then-cancelling may not apply.)