Couple of comments. First, those Mavic wheels are very strong and durable. Spoke counts are just one factor of durability. At your weight of 150, you should be able to ride any wheel without worries. I'm 165 and use Zipp 303's for my daily training and they have 18/24 spokes. Second, $180 for wheels for your Trek is a good investment but I wouldn't do more. If I were you, I would get them, continue to ride and save for a new bike down the road. There are some really great deals on year old models.