I found a set on my local craigslist for $50 brand new. I wanting to lower my wagon about 2 inches. The springs are a 1.5 inch drop but im not sure what kind of a drop ill get with a wagon. Here is a link to the springs.
http://www.bmrsuspension.com/?page=products&productid=1594&superpro=0
http://www.bmrsuspension.com/?page=products&productid=1594&superpro=0