I'm guessing she'll be disappointed, something isn't adding up. That's happened to us in the past. I'd drop a line to the customer and let them know something isn't adding up with that quote, suggest that they keep a keen eye on the proofs and estimates to make sure it indeed is an apples to apples bid. If they catch the other shop in a bait&switch because of your suggestion, you've got a stronger relationship with them from here on out.