Don't know how you feel about it, but your best bet would be Wal-Mart. I bought a 128 MB flash drive for 20 bucks at Office Depot, then went to Wal-Mart the next day and found one at 512 MB for about five bucks more. I ended up giving the Office Depot one to my aunt and buying a 512 MB for school.
Here is a 1 GB version of the one I bought.
Hope this helps.