I love www.brpboxshop.com for cupcake boxes. I got SPS off of www.fondantsource.com and 10×14 cake boards from The Bakers Kitchen.
These were the cheapest, reliable suppliers I found for those items.
I also just got brown cupcake liners off of Papermart.com for $13.35 for 500. The white liners I have were from Viking for about $25 for 1,000. All of the prices include shipping.
