I agree these can be a very tough sell.
People who think nothing of spending $60 for a new iphone case or $40 for a half assed screen protector will recoil into instant sticker shock if you want over $25 for a cedar sign - And trying to add pizazz like an epoxy flood fill or even inlay does little to entice them to dig a little deeper.
They have no concept of what is involved, and while it may be true that material is fairly cheap and labor is relatively low, obviously for most guys it is not worth turning on the machine to make $10-$15.

That said, maybe you have stumbled upon a niche where they actually do sell for a decent price, or just like making them to get your work out there at near cost. You can get regular cedar from any box store for pretty cheap, quality can vary greatly from week to week. Short of that, as stated, you'll have to find a mill or maybe start using pine.