These two requirements are basically incompatible. Buy a used vive on ebay and start there maybe.

Yeah that’s a really weird price range. I’d say go up and buy an Index if possible, or go down and buy a Quest with a fake facebook account. The pimax is an option but it’s above that range.

I picked an arbitrary number.

Let's say up to $1500. How about that?

Getting closer. Get really thrifty with a computer build (Buy a used 3600 processor for cheap and an old GPU, like a 5700xt or equivalent), buy a brand new Index, and enjoy.