Looking for an E-Commerce Plugin that Allows Multiple Add-Ons for Each Item

This would be similar to buying a car, where you choose the basic body type, then you can choose the type of wheels, radio, paint, onboard systems, etc. And the options you choose can affect the price. Each add-on type has multiple options (satellite radio, AM/FM radio, HD radio, etc) and should be able to have a picture as well.

I haven’t been able to find a good plugin that seems to have these functions out of the box. We tried outsourcing development to modify the Shopp plugin for this, but – against our directions – the developer hacked the core files and ruined the plugin.

Any suggestions of a good plugin that has these functionalities or one that is easy to modify?

Thanks,
Darrin