I got my nephew interested in shooting and his high school has an air rifle team so I gave him one of my Daisy target shooters (from CMP) last year. After months of practice at home, he managed to get a place on his high school air rifle team this past fall so I decided to investigate improving his equipment and bought an Air Arms 5400 MPR (.177) from PyramidAir via CMP. Beause it's a PCP system, there are 2 basic ways to fill the tank. You can get a K-valve yoke for scuba tanks (about $80) or you can get what's basically an upgraded bicycle pump (the Air Venturi runs $280) plus a $28 adapter (Air Venturi Female DIN Adapter, 1/8" Male BSPP Threads, Stainless Steel).

The Air Venturi hand pump is a lot more expensive but of course more portable because you don't need to tote a scuba tank everywhere. For something like a rifle team where you have a set range and can just leave the tank in a storage shed, I'd just use the scuba tank adapter and take the tank in to a scuba shop for recharges periodically but for anyone else, I'd pay the extra $$ for the hand pump (it really does look like an old-fashioned bicycle pump).

I've only shot the Air Arms a couple of times, would love to shoot it more often but Colorado Springs actually has more restrictive laws in this case than Honolulu where I could practice archery, BBs, or air riflery at home as long as the projectile doesn't leave my property lines. In Colo Spgs, I just can't go outside where I might be visible and it's hard to find enough room to set up a 10 meter range inside the house.