I wish that Colorado had someone on the list other than the GDC
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. Not that they are bad, but their prices run about $1600 now from what I understand and there are certainly assessors who have different approaches than they do. Options are good!
I can recommend a tester in Denver if you need one. We used GDC in the past for dd and more recently a new tester for all three older kids. She was recommended by multiple friends. She and her colleagues (I think one of them was formerly with GDC many years ago) test for local gifted schools.
Which leads me to another thought - many gifted schools have a list of testers they recommend to their applicants. That info is often available on-line, on a school's website, under admissions info. So OP, I'd check the websites of local gifted schools in Boston to see if any of them list psychologists for testing.