How to find a good, licensed, moderately priced plummer

Note to moderators: This post mentions pricing but I'm not asking if a given quote is reasonable. I'm asking about a general approach to search.

I live in Seattle. I got a quote from a plumber dispatched from a large company with a good reputation. I thought their quote was pretty expensive. I was especially concerned about their "stand down" charge -- it seems fair to me that they charge something while waiting for the building manager to turn the water back on before testing the fix, but the amount they were charging for this was pretty crazy I thought, and I knew it would make me anxious on the day of the work, hoping there wouldn't be any extra delays getting the water turned back on.

So I did a Craigslist search. I got some responses, but (as you might expect) I'm finding that many of the people who say they are licensed and insured are not actually licensed. (I don't know how to check whether they are actually insured, but I imagine many are not.)

I have a few questions related to this:

* Is there actually a lot of variation in pricing among quality, licensed plumbers, or are they all competing at more or less the same price points? That is, is it a waste of time for me to try to search for a significantly cheaper quote because all quality, licensed plumbers in a given area are going to be pretty closely priced?

* Is there a recommended way to find a quality, licensed plumber who charges less that the big companies?

* I don't like the way the estimation process is so opaque. Like, I paid $70 for this particular company to give me an estimate. I don't begrudge them that. They should be paid for their time and $70 for two people to look at my problems in detail is not much. Still, if I actually wanted to shop around, I could spend quite a bit on estimation visits. Now, I know that nobody can give an estimate without coming out to look at the details. But still, I wonder why there isn't (as far as I can see) a website where you could see roughly how much each company or independent contractor would charge for a given job, such as installing a new fixture, doing a typical leak repair, and so on. Again, I realize that nobody can say how much a leak repair will cost until they come and look -- it could be a simple fix or it could turn out to be quite complicated. Nonetheless, it seems to me there could be a website where you can see about how much each company/person would charge for several "typical" jobs. When I got my quote, they were looking things up in a book. They had different job levels. Like replacing a wall-mounted faucet might be a level 5 job, and they had a certain fixed price for a level 5 job. Again, I know that a given case might have special considerations, but their book still gave prices for typical jobs. In short, I guess what I want is a website where lots of companies' internal price lists like that would essentially be searchable. Does something like that exist?