At 10g, sfp+ switches are cheaper and more available than 10gbase-T switches. Fiber transceivers seem reasonable, but I could be off; I've only looked a little at fiber prices, I already have cat5 in the wall, so I'm on DAC for nearby stuff and twisted pair for other rooms for the forseable future. I don't really need 10G, but it provides a bit of fun.
Yes, I have 10g over cat5. I don't need it, but I have it.
Ethernet specs are for cabling in dense conduit. Most people don't have dense conduit in their house. Much cable tests better than the rating on the jacket.
I am using 10G over an ~15m 4 twisted pair phone cable (PTT, common in France even decades ago for ISDN, but no cat cable at all) and don't remember seeing a frame lost in quite some years.