6 card 280x rig

So in my country i can get a r9 280x for about 100 dollars of less.would it be worth it to get 6 cards and how fast would i make my money back?

According to WhatToMine, you can expect a ROI of 72 days. That is just for the graphics cards, not the PSU, MB, etc. I assumed a price per kilowatthour of $0.12 USD, but you should change that based on energy costs of your area. The fee was set to 1%, but make sure to add in the cost of anything else, like a miner’s dev fee, or a higher pool fee.