i put a NY-1 trigger spring in, plus a scherer 3.5 lb connector in my glock 19. total: about $14 from glockparts.com
this will give you a great "revolver like" trigger pull. heavier than the standard pull too.
I've run that setup for awhile, though mine was a Glock OEM 3.5 (I think they call them 4.5# now) connector. I also took the spring out of the NY-1 housing, to lighten the second stage even more. Ended up not too much heavier than the standard pull, but a lot more even. Works well if you prefer a revolver-like feel.
You really don't have to worry about the plastic thing breaking, it lasted forever for me. And even if it did break, Glocks will actually work fine without any trigger spring at all, for a single magazine, as long as you're actually shooting the gun and not dry-firing it. The trigger will only fail to reset after you reload.
Nowadays, I have an increased power trigger spring plus an 8# connector. Lots of takeup, then a very short, reasonably crisp break about on par with a plain jane 1911 trigger.
I recommend buying stuff from Lone Wolf.
http://www.lonewolfdist.com/
Avoid glockmeister at all cost, worst customer service in the industry.