I'd like to get some form of storage space for my bike. Nothing huge, but just so I don't have to take a backpack with me everywhere I go for odds and ends (especially books, as I'm returning to study this year). I just got off my L's (yay!), so I'm not too keen on extending the length of the bike or making any permanent modifications since I'm still a newbie at heart. I've seen a few people with removable textile bags that strap onto the pillion seat which I think would be good for my needs (especially since I'm not allowed to take pillion passengers for three years anyway). Any advice on where to buy these and what the price range generally is? Are these usually waterproof? My other thought was perhaps something sturdier that I could clip onto the bike instead of the actual pillion seat itself, but I have no idea if that even exists. I'm currently situated in Bendigo, but don't mind travelling to Melbourne to shop for bike stuff. I'll be moving to Canberra in a couple of weeks, so suggestions for up there welcome too.