Grouping results as a "group facet"

Great (great!) module.

Using it on a real estate listings site, I found the need to group certain CCK fields (such as size of property, price, ...) and possible "open" the group when searching in a specific group.

Example: properties are 100 - 10,000 sq. feet. and prices range from $100K - $10MK. what I'd like is to create groups: "100 - 500 sq. feet" , "500 - 1,000 sq. feet", "1,000 - ...." for the sized and possibly groups for the prices (such as "$100K-$200K", "$200K-$300K",...). A bonus would be to allow the user to then refine the search by displaying the individual elements of the selected group to search by.

I've thought about creating the group fields manually (using extra cck fields) or automatically (using computed fields). I don't know enough PHP for the second option, and while the extra fields approach seems stupid I think I'll use it for now.

Any help/thought/ideas on the subject are highly appreciated!