Jason and the List:

Try Performance Bicycles at www.performancebike.com  or
Bike Nashbar at www.bikenashbar.com.

Both of these are major mass marketers of middle to high end bicycles
and offer major name brand bicycle racks as well as their "house
brands."  Many of their very high quality racks are much cheaper than
the imported racks that I often see discussed on the list.

Many of the racks will mount on the rear of the vans and some will
hold up to four bikes.

Sam Walters