If you have that much money to spend make it yourself, I'd never fancy buying something someone else has built it's much more satisfying doing it yourself, even just getting a kit then growing it how you want it.
It took me 4 days to build my honcho then 5 months later of tweaking, playing etc to get it 100% and I enjoyed all the tweaking a hell of a lot more than the making
As Dready says, do it a bit at a time.
Buy the body, as everything is based off that.
Get axles to fit
Buy some delrin and make the chassis
6mm delrin rod and some rod ends and thats your links done
transmission, depends on body type but you can get a brand new axial one for £30
The body for my next scaler arrived today and I'm gagging to get going building everything