I used my FX Crown initially and then bought a MKII to use. I'm thinking about going to panthera next. Do you already have a pcp air rifle? If you do, just use that until you get the $$ to buy what you want.
I used to go to a scuba shop to get my tank filled, but there were a couple of times that I needed it filled and the scuba shop was either closed or the compressor was down. I finally bought an air venturi compressor and wish that I would have sooner.