Used Gaming System Build - $Good Value?

Hey guys, it took me about a week to put this system together. What do you guys think of the system for the price? Bought all this stuff brand new, wonder what I could have done if I went new. What are some cheap upgrades I could do to this rig?

Paid $300:
Gigabyte 3DAurora Case
Q6700
Nvidia 8800 Ultra
4 GB DDR2 Ram
250 GB 7200 RPM HDD

Extras:
24" BenQ Monitor
Logitech G15 Mouse
Gaming Mouse

Paid $100:
GTX 460

Sold $120:
GTX 460

Sold $35:
8800 Ultra

Paid $100:
GTX 570

Total Cash Paid $345
Lowest Possible Value of Extras: -$160
System Total Paid Value: $185