I agree that the price does seem high, yet the host coins likely cost Mr. Carr in excess of $20 apiece; this, with their being higher grade silver dollars. Also, demand for his 1964 dated dollars was apparently strong, and buyers, now re-sellers, are profiting on those.
As a parallel, consider the fact that an attributed merchant counterstamp on an old dollar can easily add $100 to the host coin's worth. Then too, look at the prices which modern-made Hobo Nickels are realizing; yet, another unusual branch on the numismatic tree. A few years from now, as has been the case with many of Mr. Carr's artful creations, there will doubtful be many collectors who will regret not having purchased one ... The old adage of "you snooze, you lose" then comes to mind. As his artful work becomes more widely known and appreciated, demand will undoubtedly rise.