Honestly, I wouldn't really pay much of a premium for NVME over SATA. I got a 960 EVO and the difference is simply not really noticeable over my previous 850 EVO SATA SSD. Windows loads a little faster. In games it often makes no difference (or it's so fast it's irrelevant). If you can get an NVME for only a small premium, then it may be worth it, but if you can find a SATA for a much better price then I'd go with that instead.
Personally, I'd suggest going capacity over speed if it is a consideration. You can get 1 TB SSDs now for a decent price, and even 2 TBs are starting to become affordable. If you can get a big enough SSD there's no need for supplemental hard drive storage at all. FWIW, I have to agree that the price of that refurbished drive doesn't look that enticing to me, over other new options.
Regarding your PSU, why do you want to get a new one at all? The EVGA SuperNovas are good PSUs, and if it is the same age as the rest of your build then it should have quite a few years of life left. Unless you want to keep a secondary machine running, I'd just save some money by reusing your PSU.