I have used cedar deeps with an added eke (softwoods mostly) for broods, as they are competitively priced and 14 x 12s are not quite so. The boxes are perfect dimensionally and reliable to assemble from the flat pack
I have started to make supers as they need not be on the hive all the time. Even so the width of finished board is just an awkward size.
I may just convert to poly for the future. For the ekes, PSE (as standard timber is almost the right size) or saw and plane myself. Don't really bother which. The last ten ekes, floors and roofs were saw and plane myself. The stands were sawn and PSE, and the feeders were PSE.
I would think there should be a lot of jointing of boards (edge to edge) for stock PSE for 14 x 12s or expensive in wider widths.
With a competitively priced poly brood around, I dont think they can be beaten on price and convenience. The rest of the hive is just bits and pieces, really, so saw and plane is the order of the day for the rest of it, or cut from PSE if it can be got at the right price - as I said in another thread, the individual bits are mostly less than about half a metre, so some longer lengths, with a shake or two, or a slight twist, can sometimes be obtained for a good price.
RAB