Here's some thoughts .... I'm a sucker for Tresrey stuff....
On a sliding 'bling' scale ...
Not so much bling and actually useful....
410 & 210 14mm wheel hexes - swap your wheels over without losing anything !
410 Hinge pins - significantly stronger than kit.
210 front wheel axle screws - change your front wheels with the same tool as the rears, don't mash the button head screw either !
210 Rear carbon fibre camber link - another option to the popular gurnell link, but means you don't need to dremel your gearbox case. You can't however get the ball studs quite as low using this one I don't think.
210 CF steering link - helps sharpen and stiffen the steering. Other options are available !
410 servo saver crank - plenty of people have had the plastic kit one break. Durango also do one (but it's not red is it?)
Semi bling
210 motor plate. Gives some not so much require heatsink, but does help make gearbox rebuilds at trackside about 5% easier as the spacer is threaded to the plate.
210 Rear toe blocks - arguably a little easier to change your toe in this way. But not a cheap way of doing things.
Battery thumb screws - only because I really don't like the kit ones and they're cheap.
Pure 100% bling
The 210 top deck bushing ... but I still bought em !! haha
Red washers ... turns out they don't make you go faster. Who knew ?
Shock pre-load nuts - help your shocks look good. Otherwise are the same shaper as the kits plastic ones.
99% of the above based upon personal ownership experience