Wow - great to see this car again - the bodyshell design in the lower photo is awesome, its an old image of this one that I have saved in my 'Bodyshell ideas' folder on my PC
Price-wise - to someone like me it has some prevalence as (I presume?) this car either placed high up or even won some rounds of the national series? This has got to give the car more value to the collector/enthusiast. Ignoring any race history, as a Losi XX which unfortunately looks to be in 'well used' condition its probably only worth between £50 - £70 perhaps less? A friend recently brought a good condition XX off ebay recently complete with spares, vintage electrics ready to go for around £45
If I was the current owner of this car & had no use or attachment to it - I would donate it back to you