I think that you should try to expand your rigs in any case, as the prices for the repaired cards are really low. The risk is small, and if everything is in order, you will get a good profit.
This is exactly what I am thinking of doing, and I simply do not really care if they are refurbished, second hand or new ones, as long as I get them on a deal
I am not affected by the current manipulated market, because if everything goes according to predictions and plans I would be making a passive KILLING
I prefer to invest in something like cryptocurrencies, rather than give my money to a bank with 0.8% interest rate(for the lulz).
I will try with two cards first and will see what's the ROI would be, maybe if i'm satisfied I'll continue expanding