Work it out on an hourly rate.
You have no overheads like lecci or premises rent, water, salaries etc. You're on easy street.
Anyway, once you get your hourly rate sorted, estimate the job by how long it'll take and add between a quarter and a half. That'll cover when things go wrong.
After a few years you'll get your hourly rate down pat, then it's easy. remember you are in this to make money though, so always, always overestimate without pricing yourself out of the market.
Always ensure you have a contingengy fund that is never touched for major disasters and add to it each year, it may never happen, but if it does you and the accountant will say "thank fuk we planned for that!". [Edit] You can use this to secure loans. [/Edit]
Beware! your department will attract PhD's and MsC's that want to drink tea all day without actually doing anything apart from postulating that their head is up Uranus.
Are you doing research or production?... cos I've done both and they are totally different...