Is this a joke?

We saw this a couple of months ago in the Guy-Concordia area and were left wondering whether it was real or not, or whether it was part of a clue in a scavenger hunt or something similar.

If it is real, I would love to know when this poor person bought their encyclopaedia, why they think it is still worth $1900, and whether they ever received any calls of interest as a result of this sign. I guess *I* could just call the number on the sign.....