In the interest of neatness for those with USB or cigarette lighter in the panel, I've been researching alternative parts...

pcDuino2 for 59 dollars has wifi on board that can be an AP, which eliminates the wifi dongle. Also has 4gb flash on board so eliminates the SD card.

The power is 5V/2A via micro usb so can be USB powered via a cigarette lighter adapter in the panel to eliminate the batteries (or in my case I have this in my panel so can just power it by that without the batteries).

Here's a case for it for 16 dollars.

And the RF receiver for 23 dollars of course.

Add this antenna with this adapter to get rid of the long-cabled antenna.

Grand total is the same ~115 dollars and will be what seems like a much neater package, if you have a means to power it from your panel.