Expo Guide targets companies who exhibit at trade shows. They send postal mail which seems related to the upcoming trade show, which you are asked to fill out for a "free listing" in the guide. On the back, in ultra-tiny, gray letters is the "$1,500" fee for this "service."

Scam is old and well-known. Expo Guide, based in MEXICO, is just the latest player. Perhaps 100's of complaint web sites exist on this particular scam. Some links below - from here you can find dozens of others. Beware!