If there are others on this board like me who have been searching for decently-priced pizza boxes (and are too shy to ask a local pizzeria), I have found a local store that stocks them in a few different sizes. Smart & Final sells corrugated pizza boxes in 12", 14", and 16" sizes, in bundles of 50. I picked up a pack of 50 16" boxes for $17.99 plus tax. With tax, the price breaks down to about $.39 a box - not too shabby when most sites charge more than that, plus add a huge shipping fee.
I will let everyone know how they work once I actually put one to use.