Lisa price should be compared to comparable 68K machines of the period. Google for 68k workstations.
Computer market was *very* different at that time; there were very specialised machines that could cost hundred of thousands of dollars for a single workstation.
Anyway, i would consider the Lisa as a needed transition machine to the creation of the Mac.
By the way, my understanding is that the relationship with Xerox was a little bit more than a casual visit ... would be happy to have more information on the subject.