I calculated once that it cost me about 32 cents to make my own frame from 2X4 wood bought at Home Depot. I made almost 200 and it felt like I was in the woodshop for weeks, ripping, cutting, trimming, routing, etc. It beat buying by mail with shipping costs. Then I discovered a commercial beekeeper nearby who sold them in lots of 100 -- for 50 cents a piece. It was a no-brainer for me. And a 20 minute drive in the country beats shipping charges.
I've also discovered that if I rabbet-joint the corners instead of box cutting and fitting them, I can make one box out of a 6-foot board. And if you buy a 1X12 for a deep, rip off the excess from one edge, and use that excess to make a bottom board.
For handles, I use a 3/4" dado and cut a slot about a half inch deep 2 inches from the top, starting in the center of the side and cutting an inch or so both left and right (I use a jig to restrict travel). When all those slots are cut, I move the gate 1/2" and cut another slot below (and overlapping) the first, the same width. Makes decent handles that don't stick out like cleats do. Cleats make them more difficult to store or to wrap black paper around.