I got a nice one at Office Depot online for 70 shipped you can find coupons online for there site and its better then going in store (free shipping). While mine doesn't adjust the back it can go down and up. Probably the cheapest you'll see at that price for a Exec style chair.
I'm actually looking for one myself but without wheels. $50 is the max I will currently pay.
Currently, I am using a babershop chair I got from craiglist. Works great but the metal clamps at the bottom are starting to wear and tear at my hardwood floor.