i can't in god conscience allow anyone to think about buying a used gpu from anywhere right now.
get the best new gpu you can afford when you are ready to buy or save more if you want more. buying used to say you got an extra tier or 2 better is not the answer. you are pretty much 100% guaranteed to be buying a mining card and only asking to throw your money away hoping/praying it'll work for a few months before dying.
there wil be some sales over the next month or so but don't expect 50% off or anything like that. last gen cards are still in stock and they want to get rid of em, so i do expect some amount off, but nothing crazy.
Don't get your hopes up for any decent Black Friday deals. Black Friday is just a way for retailers to dump unsold items packaged as a good sale or you have to buy it with what's effectively a white elephant (like NewEgg forcing you to buy a garbo PSU or motherboard with a video card)
If I were going to buy used which I’ve done in the past, is buy through eBay because I think they’ve got their money back guarantee. If they offer any protection plans that may not be a bad idea. But these days almost any card is potentially a mining card.
I’ve been fortunate but if you buy used from eBay be VERY sure you look to make sure the seller has good feedback and that you very carefully read the description. If you do a purchase that way, as soon as it arrives install the card and run it hard at least a week or two before you call it good so that way you should still technically be in the window where you can file a claim through eBay.
My specs currently is the i7 8700 with an RTX 2060, I was planning on upgrading to an RTX 2080 TI graphics card paired with the i5-12600k, I have already bought the CPU and have next to me, is there any other good graphics cards that would go well with it?
I'd say in fact according a video I saw, that a 6700xt is about equal give or take to a 2080ti. So a 6800xt should be a stronger card than a 2080ti. Consider as well that a 2080ti is at least 2-3 years old and many have likely been mined on a bit so you may put those on your avoid list.