Wanting to buy GTX Titan 6 gb for 200$ on eBay. But since the announcement of RTX 30 series cards, is this price good or bad?

I currently have a dual boot system with a gtx 660 running win/el cap, but wanted to upgrade my card, and the GTX Titan is supposed to be compatible with up to Mojave. If I wait, will I find an even better price then 200$?