For that amount you can get a 6 x RX 570/580 cards together with a nice mobo, PSU and processor, 6 or 7th generation. RAM and SSD ins not important part so you can buy anyone you want as long as you go for DDR4 RAM. Check a youtube video for BIOS mod as it is easy to do and will give you a really good boost to performance and use Claymore Dual Miner to mine for the moment ETH+DCR being the best pair. It is worth it, with such rig and actual price of Btc you can make almost 700 USD monthly. Do not lose any single second anymore and start building right away.