If that Allmand hoe is in good shape then 10K is not out of line. The engine could be several different one. You could get your choice of motors in them on some models. They usually are Kohlers is gas or Kubota if diesel.
As far as the Kubota dealer telling you his Kubota hoe will compare. I think not, the Allmand is a complete unit not subframe type hoe. I have used one and they work well for a small TLB.
It is funny that the small TLB will bring as much as a full size TLB. 10K will buy you a pretty good full size hoe but will not get you much of a small hoe.