One lipo should give you 50 amps no problem. 2 lipos with a combined 5000 mah rating and 45c, for example, would give you a whopping 225 amps. The problem comes into play with the 5,000 to 10,000 mah. That's gonna take some big batteries.
There are plenty of people running 1300mah 3cell lipos in a pwm box that easily get all day out of it.
The milliamp-hour ratings do funny things when the cells are wired in series.
Anyways, the turnigy nano-tech are pretty good, according to the drone guys, and affordable too. I'm building a 3s lipo soon and want to use a 1300 45-90c-11.1v, and that'll get me, theoretically, 58.5amps continuous.
I pm'ed mooch about donating one for testing, and he plans to test a batch in that size range sometime in the spring.
Honestly, though, not to sound rude, but if you don't know, you should do all your research, like spend a month studying, before you build. Lipos go boom in epic fashion when you try to make them do something they don't want to. They also go boom if their power goes through a part that can't handle it.