Hiking Rucksacks?

I've recently started walking with a friend and her dog and I am really starting to enjoy getting out and walking again (I used to walk for hours with Sam when he was younger but as he got older we started doing less) and Cooper loves it as well.
My friend has a hiking rucksack and it's really useful and I want to get one as well so I have been searching the web looking for one.
Hers is fab but it's an expensive brand and I've recently bought myself a new pair of country boots so can't really afford a £70 rucksack.
I've got one on watch on ebay that's cheap but it's already got a few bids on it and likely to go out of my price range.

I've seen one called an Attivo Active Bag, does anyone have any experience with this bag? Or does anyone know of any good brand, cheaper rucksacks? I would really like one with a few easy to get to outside pockets on it so store stuff in quickly and easily.