I just went to Dells website and priced a Dimension B110 with 512 MB of ram, 80 GB Hard drive, Intel® Celeron® D Processor 325 (2.53 GHz, 533 FSB), no monitor for $329 and +$20 if you want a monitor
After Tax and shipping it was $383.07
Forget about used that is DEAD CHEAP! and it even has a 1 year warrenty