For your easy-to-follow DC remote page. I set one up following your example, and it works great! I found a remote very much like the one you show, but for only ~$13 at Lowes. I got the contactor on eBay for $15 including shipping, and had the rest of the stuff on hand, so the project was cheap as well as easy. Here are a couple of pictures; the first is the box with the contactor and the remote receiving unit, and the second shows the ductwork surrounding it. It's a pretty busy area -- I've got an HVAC duct, the feed to the subpanel, a gas pipe, a water pipe, the DC duct, and a CATV cable all sharing the same space.
Lewis