which regulators? and is the $150 including parts or not?
Remember that labor on regs is typically $30/stage give or take, so you're in for $90 for labor. You then have parts kits if you don't have a parts for life program. Typicaly prices are about $30 for a first stage and $20 for a second stage. Some are as low as $20/$10, others as high as $50/$30. "Nitrox" kits are more expensive and unless they're used for deco bottles with hot mixes, Nitrox kits are a waste of money, O2 cleaning is a waste of money on second stages, and is on first stages unless you using with >40% O2. If you have a sealed piston regulator, there is extra cost associated with packing the chamber, typically $20-$40 depending on which lube they use.
Now, here are some other fun facts. MOST dive shops don't keep good inventory of parts and kits, and MOST shops will not have dedicated service staff. These guys aren't doing it all day every day so quality may not be as good. One of truths of regulators is that they are most likely to fail immediately after service.
Some shops to look at
Scubatoys-$60+parts. Never used them, but hear good things
Scuba Regulator Repair - Scuba Equipment Dive Gear Best Prices
@Dive Right In Scuba is $30/stage+parts, dedicated service technicians, good parts inventory
Drysuit Repairs | Regulator Repairs | BCD Repairs - Dive Right in Scuba
Air Tech Scuba is $35/stage. They do nothing but service scuba gear, these guys are on staff, with benefits, etc etc and do nothing else. They are expensive, but shops from all over the country send regulators here for repair.
Our Services and Rates
I can't tell you which of those three you should go to. I only have experience with Air Tech. I know that when you get them back, you get the old parts back as proof of service, I know you get a sheet showing all of the bench testing results *IP, cracking effort, etc*. I know they have an ANSTI machine in house to check total work of breathing and believe they provide that to you.