I don't give a hoot as to where you live, eat or do business..... it's all a matter of reading..... not the money world.
To me, the quote is for one sign and one sign alone, but they are using two pieces to make it. Most likely a 4' x 10' and a second 1' x 10'. Perhaps the customer picking it up doesn't have the capability of transporting a solid 5' x 10' piece of material. Therefore, the price is very doable. In fact really nice.
The OP should know this up front, as he is supposed to quote to create a comparison. How many did they ask you for ?? One or two signs ?? If you go simply from another company's quote, that's just plain silly.
For the vast majority of you.... if you can't read a simple quote, how do you read shop drawings or surveys ??