Yes the pricing does change, and quite significantly. I have worked inside the paint industry on counter sales outside sales and application for over 10 years. One thing many people do not understand is, the resins in the paint are more expensive to produce the higher the sheen goes. Therefore the company is at of higher cost making the paint, which in terms they charge more for the paint. I have seen a 15$ variance between flat-semi-gloss it is not uncommon and is not unrealistic to pay more for a higher sheen. Another thing to add is when doing samples on your wall prior to a painter coming is a good idea, however do not do them in huge squares with heavy coats, remember you are just wanting an idea. A lot of times the issue comes up of the paint not covering the sample coats, in fact it is covering quite well, however the paint sample applied is often times much darker than the wall color, creating a contrasting difference from the lighter surrounding wall and the sample placed on the wall. I recommend getting a piece of sheet rock and using it for the samples so you can move around with it etc.
Not only do I agree with what you are saying; but, I will not use Angie's List for referrals again. Their "A" rated painter did some of the exact things they are now warning against; however, they are still rated "A". I sent in a review and it took eight weeks to post it. They allowed the contractor to lie about what happened as a response. I had proof and photos. Angie's List is a scam; instead ask neighbors and friends for referrals!
Can't speak highly enough of the service we received from James and his team. I did my due diligence and met with 3 painters. If I'd have met with James first, I might have skipped the other meetings. He talked me out of some extra work that wouldn't have come out the way i'd envisioned and showed me a packet full of successful projects, happy clients that dated back to the 1970s.