I feel as if I am a master when it comes to skin care products. I think I have tried them all. So here it goes. The ingredient that is in Proactiv (benzoyl peroxide) can be found in many over the counter bars and washes for a much cheaper price. The reason the system is a "success" is because it is a system. You have a face wash, a toner, a repairing lotion, and a moisturizer. In my personal experience, the repairing lotion is the GREATEST of them all. However it is expensive by itself around 28 bucks so it is cheaper to just by the whole kit for those offers you see on TV around 19.99.
Another awesome product line is Murad. I have used it for years. I use their acne facewash and toner and then the Proactiv reparing lotion. There are a lot of different options and awesome products out there.
I also get facials. They are so helpful in clearing up my skin, they really work wonders. If I remember correctly your teenager, is a boy, and a facial might freak him out but my brother is 16 and he goes every 2 months also, and it works wonders, it really does.
The lady that does my facials has told me me a couple of tips when it comes to using Murad or Proactiv. The Murad acne facewash contains salicylic acid, while the Proactiv contains benzoyl peroxide. This is what she has always recommended to me and it really works, using those two ingredients.
This is what I do to keep my skin clear or get rid of breakouts:
Use a facewash with salicylic acid when you are in the shower (it doesn't have to be Murad there are many companies like Neutrogena that sell washes with salicylic acid.). The steam opens up the pores and the salicylic acid penetrates and really cleans out the pores, then turn the water to a little cooler to rinse the soap off because the cold water closes the pores and keeps the salicylic acid in there to keep working. Then use Proactiv or any other face wash with Benzoyl Peroxide(there is an awesome bar that is sold at regular old drugstores called Peroxyl and it comes in 5 and 10% and that is what I use when I wash my face at the sink) in it when you are just washing your face at the sink, that cleans off surface bacteria but does not really get down in the pores as the salicylic acid does.
Hope that helps!