Where can I order a set of biographies 4 school library

I volunteer in small school library badly in need of a new set of biographies for grade 6-8 reading level, general historical. I've been clicking for an hour and stil haven't found one.Sterling Biogaphies for exmaple might be suitable but the website doesn't seem to offer sets. I would have to think that schools get catalogs of this stuff all the time. Hmm, maybe I can visit my old friends at another school I used to help at...