A couple of months ago, I saw (and I dont know where - if I did I wouldnt be hunting it down now!) a bag that I really wanted for DS1, but couldnt afford at the time -it was under £40 - could have been on one of those kids designer discount sites)
The general style was a bit like the pink lining robot bag so basically kind of A4 landscape size, not portrait like a rucksack.
However, from what I remember it was rigid but soft - possibly faux leather. The nearest thing I can think of to what the fabric was like is the life book covers here
It looked 'fatter' than a satchel, and definately not hard leather like cambridge satchels which is not what I'm after.
It came in bright plain colours. No logos/patterns that I can recall.
It had at least a few pockets on the outside. I think ones on the side for drink bottles and some on the front.
thanks in advance if you know what I'm on about!