What, less than 25 bucks? Can't remember exactly, but I'm sure it was less than $25. And the instructions that it comes with are soooo clear, even I could do it. However, if you decide to get it, I have a couple of recommendations: first, rather than get a hole saw (unless you already have it), get a spade bit of the equivalent size. That was given to me as a recommendation at Home Depot, and it was a significantly cheaper to get. Got the job done perfectly; second, make sure to put the fuse in the accessory slot.

Yeah.
You may have to use some electrical tape to keep the power cord plug from jiggling out of the adapter receptacle. You'll see what I mean when you put it in and drive the Spyder. The vibrations will eventually make it come out. Even with the tape, that might still happen, depending on whether you have better tape technique than I do, which is highly likely.
Peace.