Well… try T & M (time and materials) OR just estimate how long (days/man) it will take… multiply by how much you want to charge for a days work for 1 man… then add the cost of materials plus perhaps (if you're in the business) a small overhead of say 3%… Voila!

I agree with Dave but I would go higher with the overhead, minimum 10% but this depends on your business costs; insurance, licensing, vehicle, tools, etc.