Not sure why your friends F4U went up in flames on a bad landing unless it really shorted out the esc bad due to impact damage. Thats a pretty hard hit to cause that though. A friend of mine had the H9 1.50 P-51 on electric with two 6s 5000 thunderpower batts in series and he lost it(might have gotten too slow) and when it hit the spun into ground nose first and destroyed the plane, there was no smoke, no fire, no nothing.

For batteries go here: www.Hobbycity.com
They have decent batteries for pretty cheap. A 5s 4900mah 25c battery from Flightpower costs $294 through towerhobbies.
I bought four of the Zippy-R 5s 4800mah 20-30c batts from hobbycity for $99ea. Thats a $200 saving per battery.
A fellow club flier got a 6s 4900 Zippy-rhyno 4900 batt for $129 and he's put 30 flights on it so far with no loss of output.
So, with two 5s 4800's in my plane, Ill have a 10s 4800 setup that doesnt break the bank and wont hurt near as bad if somehting goes south.

For batts through hobbycity, get at least the Zippy-H versions....but preferably the zippy-r or the zippy-rhyno. The H versons are made in china and are ok, but not really high output. The zippy-r , zippy-k and zippy-rhyno come from korea or tawain and are the same basic enerland cells found in thunderpower and flightpower. Whatever you do, dont get just plane old zippy with no letter designation as those are the economy brand and dont last long