Build your own desktop. It's simple as long as you follow directions and take precautions.
Assuming your from the u.s.
PCPartPicker part list:
http://pcpartpicker.com/p/n4Wn
Price breakdown by merchant: http://pcpartpicker.com/p/n4Wn/by_merchant/
Benchmarks: http://pcpartpicker.com/p/n4Wn/benchmarks/
CPU: AMD A10-5800K 3.8GHz Quad-Core Processor ($124.99 @ NCIX US)
Motherboard: MSI FM2-A55M-E33 Micro ATX FM2 Motherboard ($44.99 @ Newegg)
Memory: Crucial Ballistix 4GB (2 x 2GB) DDR3-1866 Memory ($24.99 @ Newegg)
Storage: Western Digital Scorpio Blue 320GB 2.5" 5400RPM Internal Hard Drive ($54.99 @ Microcenter)
Power Supply: Corsair Builder 430W 80 PLUS Certified ATX12V Power Supply ($24.99 @ Newegg)
Total: $274.95
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2012-11-09 16:08 EST-0500)
Also, get this case
http://www.newegg.com/Product/Product.aspx?Item=N82E16811129042&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&AID=10446076&PID=3938566&SID=
Use the promo code and you will get $10 off too.