Hauptners are the real deal for dispensing biologicals because of their great accuracy - not because ibr,bvd,pi3 is expensive, just soooo important. I also consider the pasturella shot to be very important. the clostridials are now coming in 2cc form so accuracy is more important here than it used to be. I use 30cc hauptners when processing in the snake, but if we're catching heads I'll usually set up line feeds and hang the bottles.
Aside from the accuracy issue, the hauptners are nicely balanced. You know how an optimal vaccination will be slightly withdrawn during the injection, I find the hauptner design really facilitates optimal vaccination.
Just take care of your hauptners and the cost gets spread pretty thin. My pet peeve: someone picking up one of my syringes and tightening the plunger and barrel. My old vet insists syringes be lubed with glycerine, and I think he's on to something.