I doubt you are going to get any "typical price" because pricing for plumbing work varies so wildly by region and municipality and vendor to vendor. And price often does not correlate with quality or quantity of the work in my experience. You will run into the same problem with other trades...and dentistry (the last regular dentist I had was charging 1/3 the prevailing rate for fillings, and did better work...and despite the low price he retired early.) Range in pricing for some things will be 3x or so.
Another aspect is that someone could quote a fairly low labor rate but use higher pricing for the tank/materials. You and I typically don't know what the plumber is paying for these things since they are getting discounts from suppliers. We can get an idea from doing price searches on the web--one way to check on Bradford White pricing for example, since they aren't sold direct to customers.
As for your plumber, it's not as much the price to me that is bothersome, it is that he's strung you along about a leak he should have recognized and addressed early on, rather than leaving you hanging. Then to charge you for the defective tank? That's not ethical, and downright insulting to the customer. So AO Smith offers up to $100 for labor on a defective tank, and he charges you $185. I see a problem with that. And who is to say he won't submit a claim to them on the tank he purchased and that they won't refuse your claim because they've already paid him on the serial number?
Here's the thing, do you really want a plumber who doesn't stand behind his work and won't take the problem to the manufacturer for you? If he's having so much trouble with a particular manufacturer that he can't afford to handle warranty replacement for defects in initial installs, then he shouldn't be using that vendor.