How long is a piece of string?

You won't be able to determine your own costs unless you go and do some practice tours beforehand with your completed kit and in the manner you intend to travel.

You have summer 2011 to do this. They need only be weekend or three-day trips or even a week-long one.

That is the time to start recording what consumables you have taken, how much they cost, what you actually did consume, what you didn't and won't need in future, and the need for running repairs (you will need to budget some indeterminables that you won't discover on your practice trips, such as tyres, chains, cogsets, brake pads, etc).

You should get a real feel for costs by the time you finish doing that.

You will need to consider that stealth camping is not as easy as it might seem, and that your accommodation costs will depend on your desire to revitalise yourself every few days with shower and maybe a comfortable bed, and whether there are in fact warmshowers hosts where you intend to stop.

Others undoubtedly will provide you with daily dollar amounts, but regard them as guidance. Only you can determine your daily budget based on your experience.