Schools in Pittsburgh are free to apply! And if you're applying without a job (e.g. if you're currently in undergrad), you're more than likely to be granted a fee waiver at most schools, if you ask for one.
Schools generally charge an admission fee to discourage non-serious applicants. It's their spam filter. If you show that you're for real, they'll probably be more than ready to work with you if fees are a problem.
As for the title question, gradschoolshopper has some details, but it's true that schools don't want to discourage that 1/10^6 applicant who has a terrible PGRE but amazing everything else, so they're not going to publish a minimum. The only reason they have minimum GPA's is because generally the graduate school (as in, the Dean's office) requires it; in exceptional circumstances they'll apply for a waiver even in these circumstances. I agree it'd be useful if schools posted something like "A typical student should have a PGRE score of at least XXX to have a good chance of admission" on their website, since I have no doubt some schools use the PGRE to sort similar-looking applications, and they have to know something about the range of scores they'll receive each year in their application pool.
Of course, in addition to small-number statistics fluctuations from year-to-year, there is probably different cutoffs depending on the subfields of interest--schools pay attention to how many openings they have in different research programs, and admit to fill those openings. It's possible some years a school will have a lot of openings in some particular field, and people with a proven interest in that research will have an easier time getting in than average with a low PGRE.