Matt,
If you don't know Jehmco please check them out. GREAT company, located in NJ -- everything from frozen food to bulkheads. They ship UPS ground and it's effectively overnight -- I've phoned my orders in in late afternoon and I had my stuff the next day.
Regarding your original inquiry, I, too, would be very interested in having an air exchanger installed in my fishroom. So if you find someone, refer them to me if they do a good job with you.
George