Is it two sided,about 18" X 24" or so with an outline of the state of New Mexico on it?If so it may have come from me.I found one about 8 - 10 years ago and sold it while I was still into the selling mode.I haven't done much of that in years;some,but not much.
That is the only sign I regret selling because I had never seen one before and have not seen another since.As you noted,it is a really neat sign for anyone collecting shop stuff in New Mexico like I do.I wish I had kept mine.Oh well,someone has a great sign from New Mexico if it is the one I am thinking of.Mine came from a shop here in ABQ.Good luck.