Refurbished components are fine to buy as long as you do your research. It's more about getting information about it rather than doing it or not. Ask these questions when buying a refurbished product.
1) Who refurbished it? If OEM, probably okay. If Jon's Electronic store down the street, probably not.
2) Does it come with any type of warranty? Most refurbs, especially OEM ones will have some kind of warranty, but not many have the 1 year manufacturer warranty like a new device.
3) Is it significantly less expensive than buying it new? This all depends on your budget and what you're willing to spend. For me, I paid $80 US for my 16GB of RAM that was $130 at the time. If it was only $120 I probably would have just bought it new, but the deal was right and it was refurbished by Kingston themselves.
I think all in all, buying refurbished things is your choice. Is it a risk? Yes. Is it a bad decision? No, not particularly. Just make sure you do your research before making that decision.