OK, sounds like you're good to go soldering, so I'm going to recommend the Rcexl switch as it's the least expensive (less than half the other one), and a small mod will let you power it from the same lead that controls it - usually channel 5, but whatever one you like. Shop around a little for the switch, they're generally 20 bucks or less.
I've attached the directions that come with it. Down at the very bottom, you'll see some picks of the mod. Chinglish directions are terrible/useless. If adding those 2 drops of solder to the board seem daunting, you can accomplish the same thing by splicing the wire marked "in" to the wire that plugs into the receiver. Red to red, and black to black.
To access that board, you cut the label along the seam on one side of the case. The halves are not glued, and with the seam split, the case will open right up. Nothing securing the board to the case. It will pop right out. You could also make the splice mentioned above in here if you're handy. -Al