Im after a new bag for my kit. Ive currently got a shoulder bag but its heavy as hell so im after a backpack to carry a medium format body with finder, 2-3 lenses and room for a flash/filters and a few bits and bobs. can anyone point me in the direction of a bag that will hold it all (preferable with rom to spare) that wont break the bank. ive only got about £40 max. i dont mind buying second hand.