The guy who won the cricket show fast bowling comp (138kph) for the Gabba test this season played for my club until last season. I never faced him because he never came to training but his opening partner who is noticably slower bowls mid 120s and it is pretty fast as far as I am concerned.
Based on some of those guys that have been clocked from my club a reasonable estimate of pace is to get a juggs bowling machine and crank it up until it seems about the same as them and then add 5-10mph (the machine appears quicker as you don't get the arm just a ball out a hole). So old mate mentioned above is about the same as 70 on the bowling machine and his brother is about 5-8kph slower and comes out about 65 on the machine. Rough but gets you an idea. Of course, you need a bowling machine handy to do this.
Interesting side note, 90mph is ****ing fast and I hate the idea of getting a bouncer at that speed.