Yea, I'm having trouble figuring that out too.

I mean, we owned a 4440. It was a nice enough machine. Paid $19,500 for it, and it had 6600 hours, nearly new rubber and a cab that had been re-done and a new coat of paint. 

At that time, I thought the price was a tad on the high side. I bought it with a 4640 with 11K hours and worked a deal on the pair.

They're solid, reliable machines, have excellent parts availability, but I just don't see how any xx40 tractor is worth over $25K, even in pristine condition. It isn't as tho they're rare, unusual machines.