Well - if you
can get hold of pallets, and assuming you have the time to play at woodworking - then you need never buy a bee-box ever again !
What I do is to first dismantle the pallets to recover the planks, then cut them to length using a cross-cut jig.
http://heretics-guide.site90.com/work01.htm (BTW - save the stretchers - they make great hive-stand legs)
Then, run the planks across a router table to clean-up the edges, before gluing them together on a flat surface, using weights and long clamps in a similar manner to this:
Then, brush over the surface with an angle grinder fitted with a flap disk to clean it up, and add filler to any cracks/nail holes if necessary.
This is what results - lovely wide planks made from seasoned timber ... and for free. Well, 'free-ish' - as there's electrickery to pay for and wear and tear on tools etc - but it's still a very cheap source of well-seasoned usable timber.
LJ