Backpacks- Price of Durability?

Cole is starting in Kindergarten in a matter of weeks and Cecily will begin preschool.  We are in the market for two backpacks, one regular sized and one mini "I look cute mom but I will probably never carry anything in this" version.  Cole's preschool pack was a shark backpack from the Gap that I was able to score on clearance and it lasted two years worth of carrying hardly anything back and forth to preschool.  So we have started looking around.  Since my children wear almost all hand me downs and Cole's school provides the supplies, this means our only school shopping comes down to a backpack.
As a child, I always had an LL Bean or Lands' End backpack.  They lasted years,had plenty of space and washed up well.  We have been perusing the backpacks there as well as Pottery Barn Kids,  though I am pretty sure many five year olds will be carrying this Spiderman favorite.

 

So is it really worth spending the extra money for a sturdier pack or do you think a run of the mill Wal Mart character backpack will do the trick?

Interested in checking out Lands' End's backpacks?  Head over to Ebates for 6% back and then you use this special code for free shipping Code Kidcolor pin4103.  While there check out their $12 rash guards for next year's swim season!