Invisalign suggestions, comments and costs

I have been considering Lumineers for a few months now until I realized I would much rather fix my real teeth rather than spend more money on a coverup. I have very small gaps between my front 6 teeth, and my 4th tooth back is twisted so it leaves a fairly large space. My bottom teeth are perfectly fine and while I have a slight overbite I don't really care to correct it.

I know there are a lot of questions below and I'm sure a dentist could answer them for me but if anyone could address them I would greatly appreciate it! I am at the very least looking for a starting point but would be interested to hear other people's experience with the concerns that I have. Thanks in advance!!!

My questions are:

1. Are the dentists usually flexible enough to give me the treatment I want vs the treatment they think I should have? i.e. I have one very small gap in my lower teeth but it is barely noticable & it doesn't bother me in the least. To save money I want to focus on the things that are important to me and don't want to deal with a dentist talking me into doing the bottom teeth for something that doesn't bother me at all.

2. Does anyone have any experience with just doing invisalign on one arch (either top or bottom, but not both)? Is it usually less expensive?

3. Do doctors follow any kind of guidelines such as $250 per aligner to determine the overall cost of treatment? Or is it usually a lump sum amount based on the case regardless of the length of time or number of alignments?

Thanks!!