I do my own for about 25 cents in parts and 45 minutes of time.
First remove the grip and safety selector. You'll need to do some work on the top of the rear of the trigger to make it fit once we start making changes with the set screws.
1. Finish threading the grip screw hole, if needed. (1/4 x 28 tap)
2. Drill and tap a hole in the receiver below where the front of the trigger bar will contact if a screw is threaded into it. Mine I drill right at 3/10" from the front of the trigger opening in the lower to the center of the hole. Pre drill an 1/8" hole before hitting it with the 1/4" bit.
3. Thread a 1/4x28 set screw into the grip screw as well as the new hole in the lower in front of the trigger opening hole. (Put it in from the bottom so the Allen head is exposed inside the trigger guard)
4. Start turning the screw in the front of the trigger until it won't drop the hammer, and then back it off just a touch until you can feel no over travel once it drops the hammer. If you want to give it some insurance, back it off another 1/8 turn. Drip a bit of loctite on the threads of the screw after you remove the trigger.
5. Start threading the set screw in the grip to pre load the trigger. You need to let it have it enough movement to let the sear catch the hammer once the trigger is released, so don't go too far. You'll likely thread it in to the point it drops the hammer, so be sure to keep a hand on the hammer to not damage the lower.
6. Once you're happy with the over travel and pre load settings, look into the safety selector through hole and notice the rear of the trigger is in the path. You now have to take out the trigger and grind a smidge off the tail off the trigger so the safety can be engaged. While the trigger is out, put a drop of loctite on the exposed threads of the set screw. This will likely take a couple test fits, and if you go too far the safety WILL NOT keep the hammer from dropping. The only fix then is a new trigger. They're cheap, sure, but have a spare. Just go slow with the grinder and you won't screw up.
7. Grind off the tail of the hammer to lighten it up some. This will allow the use of lighter springs, or you can cut a leg off the hammer spring.
8. Bend up the trigger spring legs a bit to lighten up the pull, but don't go crazy because you need some spring pressure to overcome the resistance in the sear as it releases the hook on the hammer.
9. Reassemble everything and enjoy your 1/8" of trigger travel and around 4 lb trigger pull.