If you've never owned a nitro - GO NEW. Most of the stuff on eBay that's used will require a (slightly) experienced eye to spot troubles. You get a manual, warranty, instructions, and the assurance that if something's screwed up, it came screwed up form the factory and is covered by the warranty.
The most important thing you can do with a new nitro - BUDDY UP! Find someone who knows nitros and they'lll be glad to coach you through your first run or two. This is going to save you TONS of time and frustration, and probably a lot of money and breakage.
What you need to buy depends on what comes with it, and sometimes you want to wait until you get it to get the right stuff - to add to the previous lists, tools, for example. Which ones you'll need and which sizes. Lots of leeeetle allen wrenches for these puppies.
So, definately:
- Fail safe - these are only $25 or so and the best investment you can make. If the receiver loses a signal, it pushes the throttle to full closed and applies the brake. As opposed to staying wherever it's at until you can catch it (which is, by Murphy's law, almost always full throttle.)
- Glow-start (two if you can afford it) and charger
batteries/and or pack for receiver, and method of charging
- Ditto on transmitter (8 AA size)
- 20% nitro fuel - this is the best AVERAGE fuel for cost vs. power- Squeeze-type fuel bottle
- After Run Oil or mix up your own batch, 50/50 Marvel Mystery Oil and Automatic Transmission Fluid
- Spare plugs, if you don't know which ones to get, a medium range OS 8 or MC-59 (which is actually hot but works well) will do for almost anything
- Tools! Generally allen drivers, small wrenches, screwdrivers, etc.
Optionally, maybe, or maybe not:
- Glow plug wrench if the kit doesn't come with one
- Temperature gauge
- Starter box (not likely with an RTR)
- Roto start or starter box battery and charger (ditto)