Esstentially the action of the calculate button should execute the update of a price object, which is the sum of all the options. Action script can do this, but off the top of my head it's a little fuzzy remembering what it would be exactly.
The only thing I'm wondering is why flash? You could do exactly what you're after with a little java, and use php for the backend.
The main reason I'm asking is simply because unless the user can see, they won't have a clue what your site is about or what is actually in the page. If this is a simple learning project, cool. But it might at least be something to consider before you get too far into it. Mainly because search engine's won't have much to work with and if a potential client is blind, or has vision trouble, you could lose potential sales. Also, you could lose sales from clients still on dial-up.
To be honest, you could grab something like CubeCart and theme the heck out of it to make it look like you want. It would provide some really nice features too, and be much more friendly to SE's and disabled users. Just a thought, since I have no idea what you're trying to accomplish overall.
Granted I don't see many blind people putting computers in their vehicles since they obviously don't drive
eek
, but it doesn't mean they couldn't potentially be purchasing as a gift.
Flash has its usefulness in some aspects of web applications, like what Disney did with their "playhouse" for kids site, but for something like this it really would be overkill and hurt in the long run.
Like I said though, if this is simply something to toy with, code on.
