tau:
...I have not service my reg in over 2 years, because I haven't been diving on it all that much...
Others have addressed the servicing cost.
I will address the more serious issue as quoted above. Regulator service is required at 1 year or 100 dives which ever comes first. This is life support equipment and servicing is cheap insurance or assurance which ever you preferred.
You should get the regulator serviced annually at a minimum if you are not doing 100 dives a year (we both need to work on doing 100+ dives a year).
Why?
Service at 100 dives: replace parts worn from use such as O rings and other seals and to check for moisture damage (rust).
Service after 1 year (less than 100 dives): Required to inspect for moisture damage (rust) and to replace parts damaged by the ravages of time such as “O” rings and other seals. It just takes one drop of water in the first stage sitting for a while to form rust. Now one or two years probably will not kill the “O” rings, but that drop of moisture might kill the 1st stage with rust, and it might just kill you too.
Examle: Dive Magazine story from November 2002 under "Lessons For Life" about divers who made mistakes and are no longer with us. Short version: Regulator serviced, only a couple of dives after that, closet 2 years, dive, rust in 1st stage, 1st stage failure at 100 feet, one dead diver. :11: See
http://www.scubadiving.com/training/lessons_for_life/the_danger_of_unserviced_gear/ for the full story.
Last but not least, service annually is required to maintain your warranty.
Solution, Tau, you need to dive more.