Yep, there are prizes - there is a team prize, an individual price (for weight loss (percentages) and then there is body fat test contest winner (with the use of the BodPod). And then various "random" winners for attending all the seminars, etc.
I'm a TOTAL group person - I cannot stand working out on my own and such. And, I wanted to mix things up a bit and this way it's less expensive than hiring a trainer for twice a week for 8 weeks too.
One bigger problem is that the trainer is trying to help all of us and we are all at different fitness levels. I'm the big outlyer as I'm fairly fit and the others are beginners. It makes me realize how far I've come, but it also makes me realize that I could be pushing myself harder if I had someone who could push me/keep up with me or be better/stronger than me so that I WANTED to get to their level.