The complete parts list.
Cheap is a good way to start.
You will need 6 GPU's for your rig.
You will need 6 GPU risers for your rig.
An SSD will be better for miners.
Miner powerusage is between 800-1050 Watts
6- and 7 GPU Motherboards
Take the cheapest.
4GB is enough.
A power button to turn it on!
You could always make your own!
Look for the cheapest Components using these links