OUr Former Music director was given a huge music room when our new facility was finished and he went to town! He picked warm but inviting colors to paint on the walls and losts a rugs/tapestry to hang from the vaulted ceilings and on the walls to help with sound. Hang on! The rugs were purchased from clearance areas and a couple of the tapestries were donated by a local artist (we just promised to hang a notice "donated by---)
What maybe your greatest aide right now is a design student from an area college or university. They have a set budget, the room and time frame which are what you give them (I had this kind of assignment once) and they bring you their results.
It's an idea...