MarketPress + CustomPress taxonomy queries

This might be a bit tricky.....

I wanted to add 2 custom taxonomies to my network: The first one is "brand" and the second one is "model". I believe the reasons are obvious...
I added them using CustomPress and everything works flawlessly!!!

However, here's what I want to achieve:
Let's say I have a home appliances & electronics store. In it there are some products, a few product categories, some brands and some models. So far so good...
The user navigates the site and goes looking for TV's.
When he's on a product category, I want to display the brands of the products in that category to facilitate his navigation.

Any ideas? Probably requires some custom coding which I have no problem with, it's just that this time I don't know where to start!