Marko, looks like you are going along the route I had in photography.
What to charge is always a combination of your time, material costs and a profit margin.
Assuming that you don't wish to diddle your friend, but you don't wish to be out of pocket, look at it as a small business venture.
I'm making some assumptions here but and the costs are not exact, but you should be able to get the idea.
Cost of a 36 frame film, including your total processing costs and assuming you are bulk loading. About $5.00.
If you are taking pictures of their car, then I assume you are using at least 1/3 of the film, or 12 frames. Therefore your physical costs for film are $1.67.
Paper is about $1.30 a sheet processed, for an 8x10" contact sheet. This is a fixed cost for every roll and assumes you use only one sheet of paper. 1/3 of this is $0.43
5x7" paper is about $0.80 a sheet processed, I'm assuming if only one print is required then allow for a minimum of two sheets, more than likely three sheets used. Cost here is between $0.80 to $2.40, take the middle as an average and you end up with $1.20.
So your starting costs are looking a bit like $8.30. This of course looks really bad, but I would also think that someone with your personality should be able to convince your customer that they really need a couple of extra prints to send to their friend(s). This is where you make enough to really cover your costs and if you are lucky, possibly turn a little profit.
I think in your situation you should just be able to get your physical costs back and not worry too much about profit.
The idea is that by making prints for your friends, you are teaching yourself the craft of photography, at their expense!
As for fibre based prints, you have a guide as to how you could cost the manufacturing process.
I would really be interested in finding out how you go.
Mick.
