I have two (quite successful) whitepapers under my belt. I can write your next whitepaper.
You don't put any reference to the "two (quite successful)" whitepapers. I think if you're trying to provide a service, and if you say that you've already did some services before, at least put any link of those projects..
For a full length technical whitepaper with diagrams, typesetting and review, I charge 2.5 BTC. I can also do a quicker 'Position Paper' if you want to test the waters for quality and originality.
Besides that, i think the price is too high. But just my opinion.
Good luck.