considering that mining is UNPROFITABLE RIGHT NOW, i don't see the point of spending a huge amount of money to buy a gpu to mine ETH (because there is no other coin that has not been invaded by ASICS and has been made unprofitable for GPU's) specially when Difficulty bomb is already on the plans of the DEVS as stated in the last stream of 24 Agost on youtube.
The block reward is also going to be made, EIP-1234 would reduce block rewards to 2 ETH and EIP-858 would reduce block rewards to 1 ETH per block.
i'm going to say one important thing: unless ETH goes x2 or x3 in the next month, you´ll not even get close to ROI when difficulty bomb is applied.
you have to be really mad, like really really mad to buy GPU's for mining right now.