you really should set the price before you start.

When I worked on projects before I start my full time job I would ask what the project is and try and estimate how long it would take.

Then I would work out how much I think I`m are worth a day (I have been between between £10 - £55 a day). Then balance it to the company. A small firm may not have the budget for something thats going to take months to finish, while larger company's do.

but if I was working on a model I would just set a price for that model.

It depends on the project as well. Animations can take a lot of your time so what ever you think your spare is worth. But be sure that they know why these things take time as most people think animation is easy.

Do you have to build, texture and rig everything ??
Are these people mates of yours ??

I made a interactive cd rom (with some 3d animation in it), once for the vodka bar chain "Revolution" down in Swansea. As I worked there and the manager was a close friend I said I would do it of £75 and £100 bar tab. The project took over 4 months to finish and in the end worked out that I was on just over a £1 a day. For the 56 second animation it was taking 1.3 hours a frame to render.( it was a ice caven with lots of reflexions in it