I have done so many times, but your joints need to be spot on. There are two ways- more if you want fancy joinery.
First the rabbet joint. One-half of 3/4" is 3/8". If you rabbet both edges and are able to clamp the boards tightly both for the tightness of the seams and the flatness of the boards, two sections will give you 7" and three sections will give you 10 1/2". It must be glued well and allowed to set. Bear in mind one surface will have to lie on another surface so keep in mind some material will have to lie beneath the glued boards that can be easily removed.
I do it more easily by using wood biscuits and simply butt them together. The biscuit cutter will need to be set very carefully to achieve alignment of the joints. Once set the joint is very strong.
The trade off for the price difference is your labor and your skill level.
Dovetail or finger joints could also be used if your joinery skills are good enough.
Is your time in the shop worth the price differential of the material? If so, go for it!
I lurk around home construction sites. Most of the crews will let you take whatever you find in the dumpsters. I have collected a lot of very useful material that way.
Prior to the enormous inflation beginning in '21 I would watch the sale prices of the lumber dealers carefully. I have acquired a lot of material for decent prices that way. Often they will clear inventory to rotate stock.
Bear in mind this discussion is pretty well limited to hobbyists. Commercial operations exist on expenditure of time and find it much more economical to buy pre-cut box kits. They can also acquire them at wholesale prices. If you can somehow finagle a wholesale license or get someone with a license to make the purchases for you that would help you immensely.
An addendum to consider. Using sheet stock in a Langstroth box is not advisable unless used in a Long Lang where edges can be protected.
The local commercial guy uses Advantech and makes only migratory lids out of it. I got the bright idea to use it for the entire box construction. I made a couple of dozen of both nucs and full boxes.
Some observations:
While not harmful to the bees, the composite materials make it very heavy.
It is water resistant as it is used primarily for sub floors.
It is not as permeable as plywood, and it is not receptive to wood glues. A polymer glue should be used. I joined the boxes with long gripper type wood screws.
The advantages:
Water resistant and does not delaminate easily. Edges should be sealed well.
It is flat and will not warp.
The boxes themselves are heavy, so imagine lifting one full of honey! It is a hernia in waiting.
You must use an oil based primer paint before top coating.
I have had these mixed in with common pine or Cyprus boxes. Not a single Advantech box has broken down over the last ten years!
It is pricey. I just saw 4'x8'x23/32" Advantech for around $57/sheet. One sheet can make several boxes, so it is still more economically advantageous than standard dimensional lumber.
Given the weight issue, I confine it's use to tops and bottom boards now.
I am very pleased with the nuc boxes made from it. Five frame nucs get tossed around a lot during Queen breeding. Mine have shown no evidence of wear and tear.