IMHO It was long winded and a lot of TMI.
I'd start by sharing with the potential client the fact that every date is our inventory. Our prices are set by a business model, and we stay in business by providing the best customer service at a price that can keep our business alive.
You might go on to say something like this:
It is easy to think of a DJ as lower on the food chain than a photographer, caterer, venue... untill you put my Aunt Sue with a camera (photographer) next to Ryan Seacrest with a microphone (A DJ/MC Entertainer). You have to decide if you want to hire top notch entertainment, or an amateur for your Wedding Day.
I read a few borderline-insulting things in your letter:
"Think about your jobs...What would ING tell me if I said I wanted a higher interest on my savings account? Would you be willing to take a pay cut so that I could have it? Of course not! And I wouldnít expect you to either. You are a professional at what you do and deserve to be paid what you are paid, if not more."
"Iím sorry you donít see the value in what a professional DJ can do for your reception."
"Should you change your mind after meeting with other DJs (and I encourage you to do so), I'd be happy to speak with you again, should you change your mind, but keep in mind I can no longer honor my offer of a package upgrade. Two brides that I met with this past week booked my Platinum Package without any upgrades"
This is something you might want to stay away from because it could possibly #1 cost you the sale, and #2 cost you bad publicity on the boards that the brides comment in.
Just some good healthy well-wishing advice.
All the best.