Hope I'm not breaking rules, but I put my e*thirteen TRS dropper on ebay for $1.

It's like new, taken off my 2018 JT Jeffsy. You'll want a new derailleur cable and housing to make sure it's long enough for your bike. Also the mount fits under the clamp of a SRAM brake lever, so you might need a generic bar clamp for it if it doesn't fit.