You shouldn't have to change the flywheel. No one that I know of has needed to change their flywheel when switching to the O.S. RG. You could also look into the mach .26 and sportwerks .26 both are $130-$140 (mach .26 has low end power and SW .26 has top end power).

For the starterbox I use the Ofna true start.
http://www.nitrohouse.com/starter_boxes.htm look for the part #10256. It works on 1/10 stadium trucks too just remove some screws and change the direction of the wheel. The 1/8 one is $99 but it comes with a power pannel (for a plug in glow ignitor) and a 12v battery. For the 1/10 one you need to buy a battery and switch the wheel around to fit an 1/8 buggy but it will be cheaper as well. http://www.nitrohouse.com/acces,_bat...6_chargers.htm they will have a 12v battery and charger on that page if you need it.