I have to agree with Jane. I looked at Spinning wheels a lot before deciding on which one to buy. I finally ordered the Ashford Traditional last week. I've heard lots of good things about it from several different people. The biggest selling points are the availability of Customer support, available of parts if something isn't working or you decide you want to switch from single Treadle to double or vis vs.
Make sure when your bidding that you check what the wheel would cost you to buy new. My local place is also online if you want to check prices there.
You can also find information about the Ashfords on there website.
Good luck with your search for a wheel. I had a lot of fun shopping for mine before deciding on the Ashford Traditional.