I like the idea, unfortunately the site looks like a home job and it is somewhat confusing. It's all over the place.

There is weight information for a 7.5 pound rig capable of carrying 50 pounds and 9.5 pound rig for a 100 pound load. The 50 pound Rollerpack comes with the bag and costs $295.00. The 100 pound Rollerpack is the same price but doesn't come with a bag.