Who to hire to build a garage studio??

I've just bought a house in Los Angeles with a 3 car garage, and I'm going to turn the 2 car (20'x20') into my writing studio. All I need is the writing/control room, and a small machine room/closet. I won't be doing much live recording, if at all. I've called some of the major dudes - Boto Design, Studio 440, etc. and they all rough-quoted around $75,000 to design and build this single room!! That seems outrageous to me. I was hoping to design and build for like 10-15k at the max. There is no info I'm leaving out - I didn't request something special - some crazy design, or a specific African imported wood or something....just a room that will sound good that I can trust. Does anyone know of the lesser known studio design (and build) guys that do good work for a price that reflects our current economy?

You either hire mr John Sayers or start reading this forum for quite a time mate

"I was hoping to design and build for like 10-15k at the max." That's DIY budget money so you have a lot of learning in front of you. Your HVAC will eat up half of your current budget and materials mostly the rest. Good luck.