Phantoms are the greatest pump guns around ... unless you want to spend over $700ish to buy a Carter Custom Pump.
Phantoms aren't exactly cheap ... But they're great 'guns
Check out Their website you can see all their custom configurations and such ... Their prices are quoted high ... if you shop around you can find them for much less ...
SL-68s are a cheap alternitive. Not as nice as a phantom, not as upgradeable etc. but they're just over $100 and they're Tanks.
If you happen to own a 'cocker pump kits are a REALLY cheap way into the pump game.
lets see ... what else? If you own a spyder you could buy a hammer pump and use all of your spyder upgrades and barrels on it. I'm sure I'm forgetting some viable alternatives but this is just off of my head.
-Micah