[Hikikomori]

Enterprise 10G SFP+ switches has been pretty cheap on eBay for longer than that. While you can plug in an rj45 SFP it's just cheaper and better to use DAC cables.

[zokier]

Isn't the software (licensing) situation for second-hand enterprise switches bit iffy?

[bigfatkitten]

Second hand optics and preterminated fibre are cheap now too.

[denkmoon]

First hand optics and fibre are cheap too really. I just picked up some 10GBASE-SR SFPs for $25usd ea, while an equivalent copper 10GBASE-T SFP module is nearly $90.