Step 1: Shopping List
I used two 110V solenoids out of an icemaker, but you may want to build your lock using DC solenoids. Some of them are very strong, and your options for powering the lock in the event of a power outage are greater. Just something to think about. IMPORTANT! -- Make sure you get a continuous duty solenoid, some solenoids are only meant to be energized momentarily, which will cause a problem if you leave them energized and walk away. Read up on the various types of solenoids here.
I got my X10 controller (Keychain Remote type) on eBay for about $15.00 shipped. This is a simple kit that includes the receiver/appliance module and one remote. Search for "X10 Keychain Kit" or "RC6500" on eBay to find the one I bought.
In addition to the above, you'll need 2 return springs per solenoid used, 1/2" steel dowel rod (about $6.00 for 3'), an extension cable long enough to reach your outlet with enough to spare for some additional wiring, and possibly some bits of steel for reinforcement. Depending on what kind of connections your solenoids have, you'll probably want to get some crimp-on connectors. Solder and shrink tubing work better, but are harder to get apart if you should need to.
Optionally, you can buy a couple of magnets to mount inside the recessed mounting hole. This will help the bolt to stay extended, and make a great noise as the bolt closes.
Another improvement on my design would be to use a small hobby box as an enclosure for each solenoid. This would look a lot cleaner and keep the electrical contacts under wraps.