I did a web search for replacement triggers. This page is a record of the results of that search.
It appears that the cheapest alternative is to buy a new hammer. This requires disassembly and reassembly of the trigger group, something that many people would rather leave to a gunsmith.
Then there's the Volquartsen trigger guard. This is a drop-in for the field-stripped trigger assembly. It retails for $200, but is available for $180 in at least a couple of places.
For the perfectionist, there's the Kidd two-stage match trigger. Like the Volquartsen, it's a drop-in replacement for the field-stripped trigger assembly. At $300 it costs more than I paid for my 10/22. Might be worth it anyway, however, though I'd want to talk with someone who's used one before dropping that much change.
E. Arthur Brown has some Ruger 10/22 Accuracy Tune kits. These include a titanium firing pin for $30, a hammer tune kit for $32, a competition sear kit for $30 (hammer and sear for package for $55), and a rack and roll bolt release for $13.
Jewell Triggers, Inc., Dept. PS, 3620 St. Hwy. 123, San Marcos, TX 78666
telephone (512) 353-2999, fax (512) 392-0543
http://www.gun-tests.com/performance/jan97jewell.html - an article about Jewell triggers. Jewell was planning to make a 10/22 trigger in 1997. I couldn't find a price anywhere, though I did find a discussion of the Jewell 10/22 trigger, which I forgot to bookmark.
Trigger, hammer, & sear: $132
Complete trigger guard assembly: $200
www.sportables.com/shop/product230.html - $180 for trigger guard
www.ontargetguns.com/vctp.html - $180 for trigger guard
www.bellandcarlson.com/product4.HTM - hammer reduces pull to 2.5 lbs
www.zediker.com/books/ar15/zbay2.html - hammer $25
origin.me.gatech.edu/~weage/firearms/ruger_10_22_trigger.txt - Recommendations on Volquartsen hammer kit
Kidd two-stage match trigger - $300
www.coolguyguns.com/scg_trigger.htm - instruction manual
Canjar - another trigger manufacturer according to the Guns & Ammo 2002 Annual Buyer's Guide. Didn't find any useful links.
Some other trigger manufacturers for other guns, but no 10/22 triggers:
www.timneytrigger.com - Savage 110-116 and other rifles
Dayton Traister - Ruger M77 and others
www.spec-tech-industries.com - Ruger M77
Good list of links: