I just picked up an Electronic Pistol Box made by Homak off of Amazon. It was $34 with free shipping so I thought it was a pretty good deal. Setting up the code was a little difficult as the instructions are not the greatest, but once you understand what you are supposed to do to change the code, it was pretty easy. It uses 4 AA batteries and has a pretty unique back up feature. Because it has no key lock mechanism, they put a set of external contacts underneath the keypad, so if your batteries go out, you simply take a 9v battery and push it onto those contacts and that powers the keypad.
It's not made to be a high security lockbox, nor is it fire-proof, so don't expect it to keep things safe if you leave the house for a week. It's made to keep the firearm easily accessible to the proper people and keep kids or other curious individuals from easily gaining access to your pistol.
The one I purchased appears to be out of stock on Amazon at this time, but here is a link to it in case anyone is interested. The have another model with similar dimensions that's a little cheaper, but I didn't like the door configuration on that one.
Amazon.com: HOMAK HS10036684 Electronic Access Pistol Boby, 10-Inch by 5.5-Inch by 7.5-Inch: Home Improvement