Morning, I see no one answered your question. I do a fair bit of mapping a month (right now 8 sites that are either monthly or bi-weekly). My suggestion would be to try and get a used Phantom 4 Pro and start with that. A MP3E is a huge investment with no work lined up. As far as entry points my suggestion would be to (and I know I'm going to take flak for this but it is what it is) find an aggregator that pays decently, not the $50-75 type offers but $150-200 per flight at a minimum, and get some experience there. Those flights will help you to understand your deliverables, how to set up missions, how to fix issues in the field, and what is required to fly a site of 10 acres, 50-100 acres, and over 200 acres. Try and get access to one of the processing software (they have free trials). I've used DroneDeploy, Pix4d, WebODM, and Agisoft Metashape to process my maps.
Once you have a bunch of mission experience then you need to figure out what specific construction companies over there on the west coast are looking for. What are their pain points and how can you offer a solution to help them overcome them. You're going to have to invest in either cloud processing or a computer powerful enough (if you don't already have one) to process maps and 3D models. Keep that in mind as you build your budget. Most people think that buying the drone is the only expense associated with mapping and that's why they get discouraged quickly. It costs to play in the space.
I am still trying to work out what fee structure works in Florida, what is competitive but doesn't run away potential clients . Other pilots don't ever seem to want to share info even though the pie is big enough for a bunch of us and so that's what I think contributes to pilots fees being all over the place. Other pilots who I have good relationships with outside of Florida are charging from $650 to $1300 per flight depending on the deliverables and the accuracy required. If you are involving GCP's and centimeter accuracy then that's where that higher fee is derived from. If they want Aeropoints (which are in no way cheap) then costs could go higher but again that's outside Florida. Way too may people here trying to compete and they price at rates that don't seem sustainable for the investment involved.