Here are the spares/options i would get
Roche spool
BD-008FG - Lightweight Graphite Front Suspension arms
BD-008RG1 - Lightweight graphite rear suspension arms
(Damper mounting position 39.5mm)
BD-010TP - Joint / pin (pin φ2)
BD-189L - Rear Drive Belt (Rofurikushon)
BD-301RR1 - Rear block (Makes 3d toe). Get the 45.7 rear block if racing slower classes also (17.5 and down)
BD-412W - sway bar kit
BD-412H - Aluminum stabilizer (Swat bar holder) x2
BD-201R8 - 8mm sentre steering rack (Makes car more twitchy)
BD-413 - plastic c-hub
BD-415SG - Graphite steering block
BD-415RG - Graphite rear hubs
BD-500DP - Diff blades
BD-506 - Diff rings
BD-516L - Front belt
Also a spare thrust bearing which i cant find the part number for. $2 US
There are other spares that you can buy if you like having spares. An extra diff for example. etc etc....
There are other bling parts that make the car look pretty like mine. But they wont make you go any faster
Hope that helps,
Antoni