One place with hypobaric chambers is the RAF. I had explosive decompression training about 13 years ago. Without going into too much detail this was also for a space-related experiment, in this case a zero gravity airplane flight. You had to have full safety training.
Unfortunately the flight never happened but the explosive decompression experience was, in my opinion, the best fun you can have with your clothes on. A tale for another time perhaps!
The RAF did this for me for free at the time since some of the older medical officers were sympathetic to spaceflight. They have since retired. I know this since a colleague in the RAF checked a few years later and was given a curt no for the same request. You have to pay for it now! :-(