Ebay is your best bet. That is where most of us got ours. Search for Dodge homelink. It will be rare to find, so you will probably have to look for Chrysler homelink. Then find one from a 300. There is a huge parts company that sells tons of stuff like this. LQ something. Their going price is $49 plus $15-$20 shipping. That includes the whole upper console. I looked and looked to find one where the guy who yanked it out of the car didn't cut the wires so frikin' close to the plug. The 300 is gray so we had to paint it. I taped the three buttons and used an xacto knife to cut all the tape off except where the 1 2 & 3 lights are. I pressed too hard and scratched it, but it is in a place where you can't even see it, so it didn't matter. Some guys just leave the 3 buttons light gray. There are some threads on here that explain how to do it. The one SS Dodge started is the best. He's our hero of electronics here. I put my pics on his post as well. That post tells you what two wires are the CAN B bus wires for the lights in the unit. I also ran a wire to the + feed and just used the ground by the lights in my upper console. Good luck. I had a blast installing mine. Swore like a sailor, though. Did it in July in my garage at night. Yuck. In the daylight in spring or fall would be the best.
I have all the parts, no plug or harness came with it. It seems that the harness is glued to the headliner and they re sell the headliners with the harness attached.
The plan: I bought 2 wire repair kits from Dodge (Item Number 05183472AA, about 22.00 each) they come with the 6 pin plug you need to plug into the homelink unit that is mounted on the backside of the upper console.
It takes 4 wires to make it work. From the Homelink plug: Pin 1 orange/white; Pin 2 white; Pin 3 red/green; Pin 4 black/green these 4 wires connect to the cable plug located behind the right A-Pillar. (the pillar between the windshield and the passenger door)
Programming is a little tricky. Because you won't have the EVIC display to look at. (the display in the Speedometer) So, to program you must first push and hold the two outer buttons for 30 sec to clear any old codes.
Then push and hold the button you want to program for 25 sec., WITHOUT LETTING GO! take your hand held remote and hold it up to the Console and Push the botton for 25 sec. the let go of both buttons.
Repeat steps for the other two buttons on the homelink.
You are done, it should work, UNLESS YOU HAVE A ROLLING CODE SYSTEM (Like GENIE garage door opener) if so, you have one more step:
On you garage door opener attached to the circuit board you will find a red LED and a black button next to it (you will find the circuit board under the light cover, in most cases) You must push and hold the black button until the LED flashes at a fast pace, then run to your car and push the button on the Homelink, the LED will stop flashing. (It's best to have 2 people to do this part)
Sounds like you did the same thing as me. I just pushed both the button and the remote until the garage door started working. It has been working fine ever since. I don't think my SE had a harness attached to the headliner. At least I didn't see one, so I just bought some automotive wire at Walmart and spliced to the wires behind the dash.