I have it in my head to build a super cheap mining rig. I'm not kidding about super cheap.
Before I say any more, this is my spec list. Don't panic and call the fire department.

Raygo MT MicroATX Computer Case and OEM 600W ATX
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=7730413&CatId=1509

Intel 775 motherboard combo Pentium D 3.2 GHz 1GB DDR Memory Intel D946GZIS
http://www.ebay.com/itm/Intel-775-motherboard-combo-Pentium-D-3-2-GHz-1GB-DDR-Memory-Intel-D946GZIS-/330905987847?pt=US_Motherboard_CPU_Combos&hash=item4d0b88ab07

Sapphire Radeon HD 7850 11200-16-20G Video Card - 1GB
http://www.tigerdirect.com/applications/searchtools/item-details.asp?EdpNo=5273329&SRCCODE=WEBGOOPA&cm_mmc_o=mH4CjC7BBTkwCjCV1-CjCE&gclid=CJ_Eyv3fwLYCFeR_QgodPE0ARg


Feel free to give me a virtual slap to the face to make me come to my senses if necessary.
Please know that I'm not really doing this for profit, I'm doing it because a. cryptocurrency is the future and I want to participate and b. I love building and messing around with computers.