Have you all heard about this group yet?  They are working to negotiate discounts for homeschoolers in the same way that school districts get discounts.  What they need is for all of us to join so that they have more negotiating power.  The greater the members, the greater the discounts. 

I've already joined and would encourage you all to join too.  It can't hurt.  There is no fee or commitment to buy. 

Check out their website and consider joining!