How are you guys beating 6.95 a box that build your own .
If you are making your own bee boxes I suggest a switch to Advantech 3/4" flooring sheets. They are waterproof and do not shrink or warp. I can get a sheet of Advantech from a local lumber yard for $29.98.
I can make 8 medium supers from one sheet, or 17 from two sheets, or a lumber cost of $3.53 each. (60/17)
You can get five deeps and one medium from one sheet, making the lumber cost for deeps about $5.30 ((30-3.53)/5)
Bonus, every four sheets you have enough left over to make one more deep or medium hive body.
Advantech is 23/32", not quite 3/4". If you build to outside dimensions the hive interior grows by 1/32", or 1/64" at each end, something that I think is insignificant. A solid wood hive will change more than that during a season just due to normal wood shrinkage/swelling.
This layout includes kerf and allowance for the tongue and groove sides of the Advantech sheet. Because of the T&G I make my layout centered. I make the cross cuts first, then one of the middle cuts, that way I'm cutting the outside edges where the T&G is off last.