ok you will need a nice tool box, cos you will start to purchase special tools, spares etc within the next month

The hypers are a GREAT buggy. personally id suggest getting a decent temperature monitor, a decent set of allen keys(hobby grade) spare fuel line,spare air filter, various screws, c clips, body pins,cable ties, pliers, spare fuel filter, spare glow plugs(os8's are pretty standard) make sure once you start the bugger to run it in, similar idea to the pittys.. but more precise.. keep an eye on the exhaust as you want a nice stream of blue smoke (rich) while running it in(maybe 3-4 tanks at no more than half throttle or so) then you can start to lean it out and the fun REALLY begins!
id suggest in a fail safe also, and changing the 4aa batteries in the reciver pack to a 5cell hump. depending what servo it comes with for the steering a decent hi torque/speed one would be good. and a semi decent one for the throttle and break. Keep an eye on the mesh between the spur gear and cluth bell( a piece of folded paper between is a good mesh) locktight is still your friend!
will ad to the list as i think of more things but that should be a pretty good way to spend any change you had left over
keep us posted modee, Knox bmx track is pretty good for RC as is park orchards!