My advice, if you're like me, is buy new now. Don't wait, just buy. I started off looking for a good used
B7800 with lowish hours for $10k. Three years later the waffling got the best of me and now I have a 4240 with a front mount blower on order for $32k. Maybe I'm not a good example, unless it's of what not to do.
Every good used tractor I found was either sold or too far away. All the time looking gave me more time to read up and seat time on friends tractors and a couple of dealer demo days. Of course that lead to "for a few dollars more I could also do this". It's a disease I tell you. That of course lead to looking a new class of used tractors.
Honestly I'm not sure why used prices are as high as they are. With 0% financing on a new tractors vs. 7% or more for used it quickly makes a couple of thousand in price difference not really worth it when you figure in the finance charge and the hour difference.