Maybe I am too miserly in my approach to my home recording studio, or maybe I am completely out of touch with modern studio design - especially home recording studios; but I have been in multitrack recording since 1967, and I have never had a room treatment anything like that which you are considering. Still, I have made some pretty decent and good-sounding recordings here. I have taken the approach of minimal use of open mikes which could pick up extraneous noise. Keyboard, guitar, bass, drum machine, and even autoharp - all are connected to a mixing board with patch cords when needed. If the piece underway is an instrumental, there will never be an open mike during the recording.
I have a variety of settings in reverb, delay, eq, and the like to give my recordings more of a live sound with panning to give the effect of musicians spread across the stereo field. Since I use good-quality headphones to monitor my work as I record the tracks of a song, I don't have to worry a lot about sound reflection in my home recording studio.
What kind of electronics and other equipment do you have or have planned for this studio? If my understanding is anywhere near correct, you might spend around $4000 for JUST THE STUDIO TREATMENT. If you would spend that amount of money, you would not then want to buy cheap electronics. By the way, are you planning any treatment for the floor of your recording studio? I may have missed something along that line, but i didn't see anything about floor treatment. You know, of course, that a floor stand for a mike can transfer vibrations into a mike unless you have some provision for at least a minimum amount of isolation.
Further, what is your goal, purpose, or planned use for the material you record? This question is valid because it might well make the main difference between your plan for studio treatment and mine for a minimum of open mikes, headphone monitoring, and no studio treatment other than closing the two doors which give entrance to my studio. If you are trying to make high-quality recordings for commercial use on which you hope to recover the cost of the treatment or maybe even make a profit - if this operation is going to be a job rather than a hobby, then maybe you need some kind of treatment for your recording studio; but in my case, I am recording as a hobby for my own enjoyment and sometimes for a friend or relative. Bear in mind that a goodly amount of the music which was recorded in the hayday of rock-and-roll music was recorded in rooms far less than the ideal recording studio, but they were commercially successful in that the records were chart-topping hits. One hit recording was made in a church basement with a piano that could have used a tuning before the recording session. Perhaps where I am going here is to say that you should, before you lay out your money or sign a contract for studio treatment, give VERY CAREFUL CONSIDERATION to your priorities in connection with your musical endeavor and in your life in general.
Have you looked into other bids or quotes for treatment of your studio? I have heard many times that when a large project is undertaken, it is wise to obtain at least two bids, and preferably three on which you shoot the same desired specs to all of them. I admit that i cannot give you an answer as to whether you would be "taken" if you were to use the person who gave you the figures you have presented to us; but if I have given you pause to think things through a bit more before you plop down your money or slide your card, then I have perhaps given you some benefit. There is definitely a possibility of going into a project with great enthusiasm spending bundles of bucks either on super-expensive electronics or high-priced studio setups but failing to produce anything of note because they had more bucks than skill, musicianship and knowledge of their objective and how to reach it. Whatever you decide to do in your studio, make sure that you HAVE FUN!