If you want something nice then go for the DURALITE battery set ups. Lipoly batteries of 7.4V with a regulator to bring it down to 6V if you want. They have some units that are 4,000 Mah. That will last you for a loooooooong time. 3D heli pilots can get heck of a lot of flights on the 4,000 Mah packs.

To save money, just purchase 2 pieces of 6V batteries of say 1,100 Mah and use 2 switches. You can run them in tandem, one into the BATT input another into maybe CH9. You will then have a redundant system. I am going for that in my F90, cheaper and is effective. The twin 1,100 Mah packs should give you 4-5 flights with ease.

Again, it depends on how hard you fly. In my RC car our 1,100 Mah packs do not last that long as in cars you will be using both throttle and steering servos hard so the drain is a lot. I can get up to 6 flights easily on my low wing trainer with a 600 Mah pack on standard servos when I just putter about.