We bought a vinyl cutter from
http://www.uscutter.com and make our own. 5/4 PT wood, cut, sanded and with routered edges, painted hunter green, two nails in the bottom and stickers for the front. I got the idea from a TurfNet video posted a few years ago. The signs cost me about $1.50/each before it's all said and done, and I have the flexibility to make custom signs saying whatever we want. We use exterior vinyl and so far the signs have held up great.
And since we have the vinyl cutter, we also make custom labels for identifying our equipment, logos for the golf shop, address numbers for our building maintenance department, etc....the uses are limitless and it is very easy to do.