Interesting range of opinions here. I'm a "old guy" service tech and work on multiple brands from old twin-hose US Divers to modern Aqualung, Scubapro, Sherwood, Atomic, Cress, Oceanic...
I've seen a lot of different regs and most modern "quality" regs are very well designed and constructed. This subject is far too large to get into here but I have to comment on a couple of posts out of concern for both the consumer and the industry in general.
Firstly, the service interval needs to be adjusted based on how much you dive and how well you rinse your gear. In the Caribbean, DMs and Instructors are doing an average of 300-500 dives per year and are very often not terribly diligent about rinsing and maintenance. Vacation Divers may only do 5-20 dives per year.
When I was a full-time DM/Instructor I found that 3 months (150 dives or so) was a good time to open everything up and change critical o-rings but more than anything, it was about cleaning and lubricating. For the average diver doing 100-200 dives a year, annual overhaul is generally OK. For divers that do less than 100 dives per year I still recommend annual inspection service to at least open everything up, confirm condition, clean and relubricate everything.
Even a reg that hasn't been used for a year or more should be inspected (complete disassembly) to check o-rings for extrusion and ensure proper operation.
I've also had several regs come in for service that had severe internal corrosion due to water intrusion, despite only having a few dives since last service. Other regs have come in with threads "seized" by corrosion and salt deposits from inadequate rinsing after only 3 months.
The biggest problem I have as a service tech is disassembly. Salt and mineral deposits, corrosion, combined with over-torquing can make it near impossible to disassemble regs without damaging parts. Proper rinsing and storage are SO important.
Also, keep your dive gear away from fumes / vapor from solvents, gasoline, and other chemicals as this can breakdown rubber and plastics.
Secondly, if you are trying to "cheap out" on reg servicing, you are a fool. Sure, nobody wants to waste money but is this where you are willing to cut corners?
If you don't service your regs for a long time, you ARE going to pay. Extra labor and possible replacement of parts not normally required is the penalty you will pay. Or, your reg will malfunction....
I recently got a top-of-the-line Atomic 1st Stage in for service that someone disassembled without the special tools (or training I assume), and the damage was horrific. Scratches, dents, and marring of the exterior surfaces, lost or damaged internal parts, etc... Heartbreaking! Just a word of caution. There is a little more to all of this stuff than just getting the parts and schematics, and reading a few blogs. There are different durometer ratings (hardness) for o-rings in certain areas of many 1st Stages. Using the wrong o-ring in one particular spot in a MK25 for instance, causes a catastrophic failure resulting in rapid air loss. Seen it twice!
In response to the original question, I would have charged $160 labor plus $45 for the HP Hose plus $120 for the SP service kits plus $8 for a mouthpiece plus $10 for misc shop supplies etc. So... $343 for 2 reg-sets. I've been told that my rates are very reasonable by most folks. Keep in mind that a dive shop has overhead and likely their rates would be higher.
I sympathize with folks trying to find a good service tech. My recommendation is to talk to Divers in your community and go with references.
During my years working on dive boats in the Caribbean, I wish I had a dollar for every time customers had malfunctions with regs that were "just serviced". Things as simple as hoses not being tightened to just simply not working at all. It is discouraging to hear that there are unqualified techs out there but let's face it.... there's good and bad ones in every profession.
Just a suggestion, but before you go on a "trip of a lifetime", have your regs (and BCD) inspected and then go to your local dive shop's pool one evening and give it a shakedown so you know all is well. Confidence in your equipment is a wonderful thing! Just remember, dive responsibly. Stay close to your buddy and don't solo dive without proper gear and training. After all, a human worked on your regs and we ALL make mistakes.
Safe diving and happy bubbles.