Im new to this site and fairly new to mining ive been buying and selling BTC for a while but on recently mining. Ive been mining for a little while on my antminer s5 wich was perfect to start easy to get going to set up, now that im getting more of a handle on it im ready to do some real mining and add another miner fairly quickly but in looking at all the ones for sale i really dont know what i should do and just kind of looking for some advice. I want to go to the s7 at least but looking threw whats for sale theres some nice s5s that actually come with the power supply, theres also some s3s despite the low hasing rate the pice is really intriguing, then theres the s7 wich is what im leaning towards. so like i said im kind of stuck on what i should do i could get 2 s3s for alot cheaper than the s7, or add another s5 to the one i have.. Any thoughts or suggestions will be apreciated, i want to get another one asap but i dont want to buy one on impulse and be stuck with it.. thanks for your time
https://shop.bitmain.com/productDetail.htm?pid=00020170428042759434y4DkMn010676
Seems to be one of the few BTC miners available with a potential to ROI in a year. .