I have had several people PM me asking about the audio pucks I used on my son's bed, my Jawa, and my R2 projects. These are far from ideal when compared to all the other options out there for audio, but these are easy to find and easy to work with in my opinion. They cost about $8.00 in the store, but I have seen sellers online offering them for a bit less.
Here's how I converted them to work off a standard momentary push button switch.
Here's how it looks out of the package. You should record the audio BEFORE attempting this conversion. Although you can change the audio after, it's kind of a pain. These come with instructions for recording, but it's basically holding it next to a speaker and pressing the record button.
The top comes off real easy, just push in the side tabs and it lifts off. You're going to remove the white button and two rubber buttons. Just pull them straight off. I would keep one of the rubber buttons in the event you wish to re-record audio down the road.
You should note that the center circuit is the activation circuit for replaying your audio. The other circuit (circled in red) is for recording. It's important not to touch this circuit when working, if you do, you just erased your audio.
Take a flathead screwdriver, or other sharp, flat tool, and GENTLY scrape off a small portion of the green film over the two pictured circuits. You just want to expose a small bit of the metallic filament.
Solder your wires to both the exposed areas. It won't take much.
Feed the wires through the button hole, snap the top back on, and solder the other ends to your switch and your done.
Here's a shot of the speaker side.
It should be noted that throughout this process you'll probably activate the sound at least a dozen times. If it annoys you, just remove one of the batteries until you're done.
Again, these aren't the best quality, but depending on your project, it's complexity, and your budget, these just may work for you.
Hope that helps!