I'm looking for an estimate on the total number of telescopes in the
world today that could afford an astronomical spectroscope of
reasonable complexity.  These would most likely not be amateur
telescopes, but would be used by universities, consortia or defense. 
This estimate can include telescopes that already have spectroscopes
on them and ones that could be retrofitted but do not have them.  In
addition to the estimate, I would like justification for how it was
derived as well.