Good volumizing spray for limp hair when air dried?

Is there a volumizing spray, available say in Rite Aid or Wlamart, that really works? My hair is limp, from buildup I think, & I'm going to use a clarifying shampoo when I wash my hair tomarrow, but if that doesn't help I'd like to find a good volumizing spray. I mostly let my hair airdry so I'd like to find one that doesn't need the asistance of a blowdrier. Jennifer