Not nearly as much as most would think. I have a friend that works at RS and keeps all the store returns and floor models he can get his hands on. I buy them from him at $10 each. One of the trucks was a store return given to me for free.

I have never bought a new one from RS. Others have been from lots on ebay (back when they were cheaper).

Most of the money goes into the accesories (li-ions, motors, awd kits, bearings, FETs, body kits, etc). I have only paid full price for one item and that was a stage II evo motor kit. I shop around and find the best deals. I got bearing kits for gen1 for $5 each, Fets for $1 each, body kits for $2-$5 each. In total though, I have no idea.

I will never deny a $10 xmod though, so as long as my friend keeps getting them, I will keep buying them.