Here's a stock price list:

http://www.isuzu.com/owners/accessories/vehicross.html

Your best bet is to call Merlin at St. Charles Isuzu in St. Peters, MO.
Toll Free: 800-727-8066
Phone: 636-441-4481

Free shipping and they discount to members of this board. Use them for the Yakima cross bars and risers (called "Aero Roof Rack" on the list above). You may want to get the mighty mounts from them as well. Once you have those pieces, you can buy most other Yakima accessories to bolt on from you favorite supplier.

There's more information here:
http://club.vmag.com/ubb/Forum39/HTML/000414.html

-- Best, John