Something you mite want to do is read the Bag or No bag thread here, you may find some info and opinions there on bagging. Something else you may want to consider is using a good set of mulching blades when you mow, like Gator Blades. They can make a lot of difference in your bagging needs and they're a lot cheaper than a bagging system would be.
How many clients or lawns are you planning to cut in a day.