> It was much more expensive than I thought it should be

For 10G with copper, short runs will work fine on most anything (10m), with longer working ok on cat-5e cable (20 - 30m or so).

So, if you have existing wiring, especially in wall, just give it a try first, before gutting things. Most 10g ethernet adapters give you BER stats to see the error rate.

And, if there are issues, multi-gig may be an option, where it will drop down to 5 or 2.5 gbps, which is same as 10G, but with a reduced symbol table to handle the lower SNR.