We need to educated the customer!
Nonsense. If anyone needs a bit of education it would be yourself and others of the same bent.
The original question is bogus. It assumes that either or both of the propositions pose a problem. Therefore, if not equal, then one must be larger than the other. The premise of the question is fallacious, assuming things not in evidence.
To a client a sign that says 'XYZ' is a sign that says 'XYZ' It makes no difference to them whether it's knocked out on something flat and white with adhesive letters from Home Depot or a major work of art using the most exquisite materials. It's still a sign that says 'XYZ' and that's all that it is.
It's the height of folly to blame a client for seeking the best possible deal on a sign. Lots, if not most sign makers, view themselves and their product as something special and unique. While it might be unique in the Aristotelian sense that everything is unique it's not special.
Signs are a commodity. A fact known to everyone except sign makers. That they are not a commodity is an delusion from which the most remarkable and entertaining rationalizations spew forth.
Signs are fungible. A sign of a certain size and material that says 'XYZ' is seamlessly interchangeable with any other sign of the same size and like material. A sign maker might notice the difference but it's an odds on bet that no one else would.
Unless you can offer something tangible and of value to your client, be it price or turnaround time or something, you might be in the wrong business.
As in many professions there are lots of sign makers that are dilettante twits who, once they fail at this, will be off to something else.
I await now the always amusing tsunami of tortured reasoning from irate sign beings trying to explain just how it is that what they do is special and, being special, somehow must command a higher price than some other like product. It's what I live for.