Selling my original aqua blue 3DS with loopy's mod. Asking $380.
NOTE: This 3DS has more than just the video mod. There is an extra jack (a micro hdmi jack) next to the headphone jack that gives access to the button contacts (up, down, left, right, a, b, x, y READ: NO START, SELECT, HOME, L, R ACCESS). The buttons operate on 1.8v logic. This can be used to control the 3DS through "virtual" button presses via a microcontroller, such as the Arduino with a logic level shifter. (I know the BeagleBone black has a 1.8 volt reference pin you can use for the shifter). Ever seen that youtube video of the guy farming shinies? This is the same thing.
This is a used 3DS purchased on the release date, so it expectedly has some normal wear on it, mainly some scuffs on the outside (I tried showing them as much as I could in the picture). I do have some plastic treatment stuff that I can use to easily buff them out. Screen's have had protectors since day 1.
Loopy's mod is pretty clean/professional, so a 3DS with the mod is pretty easily serviceable. The button mod makes it not so easy. It is a handful of loose 30awg wires that are fairly fragile if bent too much. I have had zero problems, but please keep in mind that this 3DS is NOT EASILY SERVICEABLE, AND COMES WITH NO GUARANTEE OR WARRANTY. I'm not a bad guy, so I'll take a look if you have problems right after getting it, but I promise nothing! If you do repairs yourself, there is a chance you will break the button mod (although the video mod will probably still be good after that. You'll just have a useless extra jack on the bottom of your 3DS).
The circuit I use with my button mod is based around an Arduino and is set up on a breadboard, as the videos show. I'm not including the circuit. If you want to pay an extra $30, I could build it on a perfboard or even an Arduino shield for you (no Arduino included). Either way, I'll give you my [not very neat or commented] code to run it, if you want. I don't really recommend getting all excited about this "feature" unless you have programming/ electrical knowledge, or are willing to learn. I did it for fun/experimentation, not really for practical reasons.
BASIC VIDEO:
http://youtu.be/gJCtMSvpGxg