Looking for Product Comparison tool

My company is willing to build an intranet site with product comparison tool. The idea is to build a product database with compare features. The salesmen could select 1 or more products and display them side by side for comparing.

We see 2 options: custom development or off-the-shelf.

Since a lot of web sites (mainly eCommerce sites) provide such features, I'm thinking that tools are available out there. Unfortunately, searching in Google gives me thousands of results but comparing cell phones or other services, rather than "featured comparing solutions" range. I'm wondering if all those web sites have developped their own solution or used a mainstream existing product (open-source or proprietary licensed).

Any suggestion welcome. Thanks