Hi Daniel,
scrapbook.com has some discounts on most things compared to retail.
I noticed that I Brake for Stamps has some clear acrylic blocks for really really cheap in the clearance section. Not sure if those are sizes you are interested in or not. I am on their design team now and you might be able to use my coupon code SAVE10HEIDI on the clearance price, I’m not sure if it is only for stamps or not.