A-frames aren't hard to make, really -- just time-consuming, as they involve quite a bit of cutting and joining. I had to cut six 3*5 sections of plywood out of full-sized, 4*8 sheets, using my circular saw:
My weapon there is a fairly cheap Ryobi saw, which gets the job done for my purposes. If and when I get more serious about this stuff, I may upgrade to a higher quality saw, but for now, this one's just fine for me. (Although, when I bought it a couple of years ago, the first thing I did was to replace the enclosed blade with a better one, a blade that had twice the number of teeth and a thinner kerf to boot.)
The 3*5 plywood sheets were for the faces of the signs; I built the frames themselves out of 2*4s which I cut down to proper sizes using a miter saw. I then joined the 2*4s together using one of my favorite gizmos, my pocket-hole jig. Pocket-hole joining is amazing to me: not only do they result in strong joints, but they're amazingly easy to do. Here's the jig in action:
You just clamp your workpiece in the jig and then use the bit that comes with the jig to drill your pocket holes. Then, afterwards, you simply drive your screws through the pocket holes into the piece you're joining to the pre-drilled piece, and everything gets pulled together really nicely. I love the pocket-hole jig. Long live the pocket-hole jig!
Unfortunately, I didn't think to actually take photos of my finished signs, so imagine they look kinda like this, but with better carpentry and no skateboard dude.