Firstly, the "Test Fee" the shop is talking about is something that THEY are doing. While it is customary to charge a fee to take the course, that usually covers all the materials, testing, etc. What it usually DOESN'T cover is additional confined or open water charges if the shop has to rent additional pool time or boat trips; additional air fills, and the like.
You are responsible for your own PADI membership fees, just as you have been all along. Initially, this was just the cost of your PIC to get your card. Now that you are going Pro, you are required to be a professional member of PADI. Call PADI to find out what your yearly dues are: (800) 729-7234.
If you want to teach DM-led programs, you will need liability insurance. There are a number of sources for this like Witherspoon, Willis, Vincenzia & Buckley. Each one will give you their own quote. Alternately, if you are working through a shop, they should cover you through their own insurance.
Once you are a certified DM, it is up to you whether or not you want to pay to keep your membership updated &/or be insured. You CAN retain your membership without being in Teaching status by simply paying your PADI membership dues. However, you would not be able to teach any DM-led programs without insurance unless you are working for a shop who will cover you under their policy. Likewise, if you work as a Certified (teaching) Assistant in courses, you would be covered under the shop's policy.
Frankly, there are too many cost variables for PADI to put out a brochure. EACH shop or Instructor is free to charge whatever price they wish for their DM course; it has nothing to do with PADI as a certifying agency. It's only when you decide to go to Instructor that PADI directly has input into the fees associated with the Instructor Evaluation because THEY are the ones who administer it.
At this point I would suggest doing a little research into what PADI shops are charging for the DM course in your area. Talk with the shop, the Instructors who will be training you, people who have taken the DM courses. THEN you will be in a position to make a more informed decision.
Bonne chance,