I'd happily consider working for 75% of market rate, if I could work a 60% week. Add to that the ability to work remotely and things can start to look really enticing. If on the other hand you expect someone to work 100%, plus unpaid over time, plus be in the office every morning by 8 am, plus being on call, plus an absolute minimum of vacation days, and still only want to pay them 75%, then hiring will be almost impossible.

If you really can only afford 75% of market rate, you can probably still get good people if you're willing to be flexible on all the other non-salary aspects of the job.