500$ Bitcoin mining PC

Solution
None. Bitcoin mining went out as a profitable enterprise several years ago. Today, what you would earn in Bitcoins wouldn't cover the cost of the energy your Bitcoin system would consume.

-Wolf sends
I will agree nothing PC related will make you money now. They make machines just for this now and even those you have to fill a room with to make it worth your while. Little info what you need to make a dent.
http://www.coindesk.com/kncminer-plans-16nm-bitcoin-mining-asic-launch-2015/
Info in general
http://coinbrief.net/bitcoin-mining-asics-2015/

Thent