I bought a 10 gallon aluminum turkey fryer off a guy on craigslist for 30 bones. It isn't the best looking pot around, but then again I don't have it sitting out on the counter with flowers in it either.
I started out with extract and it worked plenty fine, and now that I do AG it works just the same. No issues with boil overs, even before I started adding Fermcap-s. I would suggest going ahead and getting a larger pot, rather than having to buy a larger one later and wasting money on a small one at first.