DS had sleeping bags til he was about 2.5. We never bought the expensive ones, just regular ones from KMart or Target, and Pumpkin Patch or Myer (never paid more than $30-$40). We never had a problem with zips breaking, though one from Pumpkin Patch did get a frayed press stud. Several had press studs at the bottom so we could fold the bottom up and it lasted longer - I actually added my own to a couple so they lasted longer too.