Search for J1000 and you'll find the one I got for $150. Amazon didn't have the Nissan/Chevy version for sale so I bought the Ford one. It's the exact same rack, the only difference is the bolts that attach to the van roof. I had some of the correct Metric bolts sitting around but you can get them at a hardware store for a few bucks.
I use carriage bolts to hold things to the rack or you can use attachments for Yakima racks with the T-slots.
I use carriage bolts to hold things to the rack or you can use attachments for Yakima racks with the T-slots.