Just went by my local Target yesterday and found three PoP sets on clearance including...
7569 Desert Attack for $7.50
7570 The Ostrich Race for $14
7571 The Fight for the Dagger for $20
All of them seem to be somewhere around 30-33% off. My store didn't have the two bigger sets so you might want to check. I'd expect the prices to be something like $35 for Race against Time and $55 for Battle of Alamut. Or something like that.
I bought Ostrich Race because I already had Desert Attack which I got for $6.
Oh, and they had Ben 10 on sale for $10 too.
Let me know if you find these!