A spinner on Ravelry is offering her single-treadle Traveller for sale as she can no longer use it due to a disability.
She's asked people to make her an offer, so I don't know how much she wants for it.
It's in the For Sale thread in Ashford Spinners.
I have a secondhand single-treadle Traveller myself, and I absolutely adore it. I would thoroughly recommend this type of wheel for a beginner, and/or for someone who wants a wheel to take to Guild meetings, etc., and drives a car. The Traveller is small but doesn't fold, so not ideal for public transport, but sits on a seat in the car no bother.