All my friends are mean to me and control me, so when i come back to school I want to be different than them?

My friends are very mean to me sometimes and then they are nice to me. I do everything for them that I can do, but they only do things for me when they feel like it ( never ). They ditch me and they have sleepovers and then show me pictures and say why weren't you there and then act all sad for me and say we will invite you next time and stuff. They also control me all the time, when they want something they tell me to get it, they only let me act a certain way to people ( to geeks they make me be mean and to people they hate at that moment they tell me to hate them and if i dont i have to sit with the loners at a random table at lunch and they will bully me for the rest of the day ). They also leave me out of every conversation ( they huddle together and tell me i have to watch the bags on the table and if i dont they will be angry at me cause all of their stuff will be stolen and other stuff ). Its the summer now, and i want to come back to school being myself. So I need some cool stores that have that kinda tomboy/kinda girl clothes so i can express myself in my clothes ( make sure they arnt really price like 60 bucks for a plain striped t ) and accessories. And if you have any friendship tips please give them to me.