My company is in the process of creating a Fitness DVD for our
customers.  The customer base ranges from teenagers to the elderly. 
The DVD being created is trying to be a cure-all for any age group. 
It consists of beginner, intermediate, and advanced sections of
workout.  It will be mostly aerobic, with workout bands and a Swiss
ball used occasionally.  My question is three fold:

1.  Are there any DVD's currently available (in a single disc or set)
that try to appeal to all age groups?

2.  How often do people change from one Fitness DVD to another? 
People tend to get bored with these types of DVD's and I am trying to
figure out what type of shelf life ours will have.

3.  Is there an average price that people are paying for a fitness oriented DVD?