Help?!? How to style an outfit???!?

Okayy, I really love bright bold colours and funny tee's and I am OBSESSED with david and goliath but I don't really know how to put the outfit's together and also I don't want to pay the extreme prices that david and goliath expect's us to pay so does anyone know where you can get either cheap david and goliath clothes or david and goliath styled clothes?