Try giving a few places a call. For instance, call the scuba place and ask if they know of any other places to do HPA refills. Sometimes places like mc sporting goods or dunahms does them, and someone at the scuba shop is probably bound to know of another HPA refill place.
Yeah, sadly Dunhams and Dick's (at least all of the locations in my area) only fill CO2. This issue I'm running into now has to do with the colder weather unfortunately.
EDIT: Sea The World Scuba in Farmington on 10 mile Rd & Middlebelt can fill up to 5k PSI.
Lone wolf pro shop/indoor paintball fills HPA. I have a membership so refill is free but i think it is like $3 or something.
Allow me to reintroduce myself.
2 years of inactivity, still having our team tagged in Youtube to get views.
WE Tech M14 GBBR 500fps
KWA KM4 Commando
KWA Raffica NS2