I'm experimenting with ideas for a future website and I want something similar to this screenshot:

http://screencast.com/t/ADfZZlv9

The calculator:
I am thinking of making the numbers rise to the prise tag instead of just showing it. It must have addition and subtraction abilities, as well as listing selected products in two places - one for overview and one for e-mail.

Does anyone have good experience with this sort of coding, or is there a company doing this for a living and licencing their stuff?

I have almost no experience in coding javascript myself.