I searched the internets high and low for a good deal on the necessary Yakima Wide Body Bracket (8008001). No such deals existed. I finally broke down and bought two sets for a painful $36 each on Amazon. These mounting brackets, fortunately, were my only full-priced purchase in this budget roof rack project.
Yakima 1A Raingutter Towers mount to the faux gutters created by the brackets. I found a set for $40 on craigslist, complete with lock cores! The retail price for the towers and locks is $215, so this, like the Vanangon itself, is definitely another CL success story.
Yakima's 58" version, which retail for $70. Yakima crossbars are simply 3/4" galvanized steel pipe with a pvc coating. I knew that I could buy 10' of 3/4" galvanized steel pipe at Home Depot for $12, which left me pondering whether plastic coating was worth an additional $58. I think not. I went with 10' of pipe and the friendly staff at Home Depot cut in half at no cost, leaving me with two 60" steel crossbars. The end caps are free.
1. Determine your rack placement. I decided to mount the rack at the very rear of the van, where the connection points (of the pop top to the van) are strongest. There's no perfect placement. You might decide to mount them as far back as possible (which I didn't quite do), as GoWesty suggests. I placed the front and rear brackets so the bars would be spaced 36" apart, ensuring maximum compatibility with Yakima rack add-ons. Mark the holes. Measure twice, drill once.