Most of the time I think getting used stuff is worth it, but you do have to be extra discerning. It helps if you have experience buying used and have developed a sense of when you're getting a good deal and when you're getting scammed.

I've bought about 3-4 computer parts over EBay, and only got burned once: an old $25 SAS card that ended was listed as the wrong model and didn't work for my use case. The model that's recommended is usually around $75, so it was one of those "too good to be true" kind of deals. Though I complained to the seller and got a refund.

If you buy over Craigslist or Facebook and arrange an in-person pickup, you can ask to have them power on the system to confirm everything is working before buying.

I personally don't trust used storage, particularly hard drives, since it's hard to completely erase what's on them and you have no idea what's on there. My policy is to always buy storage either new or manufacturer refurbished.

Also, if you're looking at 1080p 60fps, most new PC's will handle that fairly well