Auto-update table based on selected options
or like this...
Anyone have a good recommendation?
I think you'll find both those sites are database driven, so you'll need to use ajax.
This seems like a pretty common thing that might have a pre-packaged solution, anyone have experience with one?
I doubt you'll find a pre-packaged "just add water" type of solution. If you don't want to build your own, as a last resort you could try using one of the free open source CMS systems.