I've been looking into air rifles myself. I don't like precharged air, too much hassle, so I looked into the pump and spring guns. I was looking for power and accuracy. The best I've been able to find from my research are these:
In .22 cal (my choice when I have the money to blow on it):
PATRIOT EXPORT by Webley & Scott Ltd.
Pellet Weight 14.4 grain - Muzzle Energy - 27.07 ft/lbs
0.22 - 920 ft/sec - $465.00
in .177 cal:
HUNTER 1250 HURRICANE by Gamo
0.177 - 1250 ft/sec - $399.95
Both are break-action spring rifles, so no need to charge then up from a scuba tank.