Something that would have been cool when I started is a set of tubes that could be passed around for auditioning. I don't mind paying for something that I like the sound of, but it gets expensive to tube roll when the desirable tubes demand a premium. I've spent at least $500 so far on tubes over the last 2 months and now have my favorites which total about $200 (5998, GB6080, 6080WB graphite, T-S 5687, Syl 12BH7, CBS-Hytron 5814WA).
Extra tubes that I'm no longer listening to: RCA clear top, RCA long black plate, CV4003, Sylvania 12AU7, Westinghouse 12AU7, RCA12BH7, Tungsram E80CC, GE 5814, CV2984, GE 6080, RCA 6AS7G.
I wouldn't be adverse to sending out my unused tubes knowing that they will come back. One way to guarantee their return would be to take a deposit which would be refunded upon return of the tubes. One risk I'd have to deal with is tube failure when not in my possession.
Thoughts on this?