Great find. You couldn't come anywhere near that price for new stuff. I always preferred a little character in wood flooring, rather then the uniform looking high gloss floors you see mainly these days. Don't forget pics when your have it finished. :thumbsup:
Even with installing it over the full basement you should put down an underlayment to help reduce noise (squeaks). Even with stapling every 8" the wood will still contract/expand with changes in weather cycles, not much but some. I would mostly use red rosin paper when doing an install, but if your basement is damp then go with a 15lb. felt to create a moisture barrier so you avoid cupping. 2 1/4" oak is not something we see cup very often, unless you have a damp space under it and don't put down a barrier.
A box of 2" flooring staples should be plenty for your place. There is 7000 per box. Do youself a favor and either spend the money on a good pneumatic stapler (Bostich) or rent a good one. Also get quality staples. You do not want to be wadding up staples every third board.