I'm leaving to study/travel abroad in May. Instead of bringing a suitcase, I'm going to be bringing a backpack since i'll be traveling for a bit after my program is done. I'm just wondering what the best travel backpack is for my dollar. I'm a 5'4 girl weighing about 130 pounds. I don't want to go over $170 and would prefer a detachable daypack. I'm new to this whole backpacking thing, so the more info you provide, the better. Thanks!