What JPT is describing is the way to go if you want to save the maximum amount of money. I can do that auto bolt mod in 15 minutes with a small half-round file.
I can save you $10 more, too. Cut your own buffer from a piece of 1/4" black Delrin rod. It will work as well as anything else you can get.
I got a Bell & Carlson extended mag release at Midway for $4. It's injection-molded plastic, but I like the size and shape of it better than any of the others. It won't ever break, there's no stress on it. /ubbthreads/images/graemlins/confused1.gif
I tried doing my own trigger job years back (without a decent guide to reference) and it didn't come out being all that good.
That doesn't mean a lot of other people haven't been successful, I'm sure they have.
Here's a guide, you need a decent vice to pull it off, though.
10-22 hammer modification
If you have one 10-22 to do, don't have a vise and stones already, and are afraid you'll screw it up and end up with an unsafe firearm, this set starts looking pretty affordable.
Power Custom hammer/sear set
That gives you a sear with adjustable pre-travel so you can adjust all the take-up out. You don't get that with a "do-it-yourself" job, because that Ruger sear is too hard to drill and tap at home. It makes a crisp, light trigger and it's perfectly safe. Use all the Ruger original springs, they work great.
It costs $70, which is a fair price for what you get, in my opinion. Not everyone would agree, I imagine. /ubbthreads/images/graemlins/confused1.gif