$28 is still a fantastic price, so don't feel too bad. I bought Mirror's Edge used from GS for $35, LBP new for $59.99 & Bioshock new for $49.99 last Feb. Talk about buyer's remorse, lol.
Just picked up the last copy at my Best Buy (that I hid behind a bunch of Guitar Hero 5 boxes earlier this week) as part of the buy 1, get 1 50% off on PS3 games deal.