there is some info missing from your question, like your intended use, how long your run times need to be. What exactly are you struggling with? brand? capacity?
In my opinion though, get a quality 4s battery. I use a RX8 and T8 1900 in 3 of my 1/8 race rigs. There are many good batteries available, but I have had great success with SMC batteries. I use the 6500mah and it has great punch and more than enough capacity to complete a 10min main and not too expensive.
http://www.smc-racing.net/index.php?...ory&path=67_96