I have a 1999 Buick Regal GS. I was wondering does anyone know where to purchase one of these from. I can't even find it on the internet.

Spoke with The Google. Looks like many folks recommend a RAP solution by Dakota Digital: http://www.dakotadigital.com/pdf/pac-1100.pdf

If you use it, please let us know how it works.

So I appreciate the link. I've searched high and low on the site and all I could find was the PDF. No part, no price on the website.

I could not find that PAC 1100 via that Amazon Link, maybe I was just overlooking it.
I did find a newer version for sale, the PAC 1300

http://www.dakotadigital.com/pdf/pac-1300a.pdf

Dakota Digital Retained Accessory Modules PAC-1300 - Free Shipping on Orders Over $99 at Summit Racing

I don't know if it makes a difference but the one I was looking for was the RAP that sustained the power for my radio. I currently have an aftermaket radio with no power. It'* just horrible riding around with no radio after I spent so much money getting it installed. If this will work done and sold. I just didn't see any place for hooking up the radio. I guess it wouldn't matter if all I need is the ACC

Ok so that is not what you want.
Are you totally bypassing the Monsoon system that was in there?
Like I know you have a new aftermarket deck, but do you have a factory under seat amplifier, usually the Monsoon systems have them, but not always.
If you do have that then your radio won't work unless you bypass the factory amp, and run through an aftermarket one.
If the radio already plays through the speakers, and you just want the door warning chimes back, then you want a RAP module, which I am looking for now.

I thought I could find it via crutchfield.com, I see a kit that says it keeps RAP, but other than the dash install bracket, and wiring adapter, this is all that they have.

PAC SWI-CP5 Steering Wheel Control Adapter Connects your car'* steering wheel audio controls to select aftermarket car stereos at Crutchfield.com

Ok wait, this should work according to this.

""
PAC SWI-CP5

You want to install an aftermarket stereo in your vehicle, but you hate to give up the convenience of your factory steering wheel radio controls? No problem. PAC'* SWI-CP5 adapter allows you to use the steering wheel audio controls in a wide variety of vehicles to command select radios from Alpine, Clarion, Dual, Jensen, JVC, Kenwood, Pioneer, and Sony.
More features, easy programming

The SWI-CP5 adapter allows retention of steering wheel audio controls, rear seat audio controls, and retained accessory power (RAP) in a wide selection of vehicles. You can also assign two radio functions to each SWC button by using short press/long press functionality. The SWI-CP5 works in vehicles with either data or analog steering wheel control signals.

Installation is straightforward — connect a few wires, then program the adapter for your particular car and your stereo, and you'll retain the convenience of your steering wheel controls. You can program this adapter with your smartphone, with your tablet or PC, from a USB flash drive, or manually. The direct connection to the stereo eliminates the need for an infrared emitter, allowing the adapter to function even in bright sunlight. Step-by-step LED confirmation makes programming easy. Once connected, the SWI-CP5'* failsafe memory will learn up to 12 stereo functions, retaining them even if battery power is interrupted. Warranty: 1 year.

Important Note: On some vehicles, you may need a voltmeter to locate the correct wires to connect to the SWI-CP5. If you have no car audio installation experience, you should consider professional installation. The SWI-CP5 works with most Alpine, Clarion, Dual, Jensen, JVC, Kenwood, Pioneer, and Sony car stereos that have a wired remote control input or a dedicated steering wheel input.

Wiring Advisory: You'll usually have to tap into one to three wires in your vehicle at the radio location to connect this interface. If you're using a PAC wiring interface to connect your new car stereo to your vehicle, then it most likely will have a prewired connector for this PAC adapter so no wiring is required. PAC does provide custom wiring instructions for all confirmed compatible vehicles on their web site.
""

Currently I just have the radio. I'm not 100% sure how it'* wired because it was done by an AutoTech at Best Buy. I will be adding after market speakers, sub, and amplifiers. So I don't know how it'* wired. He did the trouble shooting and told me the RAP was the issue.

Hmm, that is odd he'd say the RAP was the issue, the RAP should not keep the radio from sending music out of your speakers, well the front at least, it will only come out of all speakers if you do not have a factory monsoon amp..
If you have a factory monsoon amp you'll hear something come out of the real, but not full range audio...

Do you get sound out of any speakers at all?
If no have you checked the decks fader/balance settings?

I have this in my car already. I'll take the previous mention models to him and see what he says. He'* currently on vacation and I'm not very trusting of the other AutoTechs. My other option was to go to dealership and start the hemorrhaging from the wallet.