Something else you could consider as an alternative to renting studio time to do a proper demo. Rent a digital portastudio and a few condensor microphones and do the demo yourself, and then mix down directly to your hard drive and master to CD from there. It will be cheaper, and you'll have total control over the sound, and you won't have to watch the clock or the meter running, and can take your time to get it exactly the way you want it. Most large music stores that handle p.a. rentals etc...rent porta-studios. Look into either a Yamaha 8 track mini disc system, or Roland or Tascam. When you submit the demo, put about 5 or 6 tunes on the CD, and edit them all down to no more than a minute and half each - showing different styles, versatility, etc. Leave the listener wanting to hear more. Don't overload them. Most people will listen for 20 seconds and if what they hear doesn't grab them within that time frame they'll skip to the next track, and so on and so on. Best of luck.