I don't believe the majority of studios sign customers to a contract. I could be wrong about that but in my 30 years as an audio professional the only time I've signed a "letter of agreement" is when the project is very large and I have to make a huge time/money commitment to the project. I do a lot of location recording and I don't travel anyplace far without a letter of agreement. Outside of that, I don't make any of my clients sign anything but a check. I do however make them aware of my policies and rates.
If you are going to charge something other than your rate, such as a percentage of profit from the sale of your clients' recordings, then you would want a contract. If you search, they can be found on the web.
Barry
