Postcard's originally sold for a penny and cost one penny to send. Once received people often kept the cards in albums as keepsakes and as colorful collectibles. Today, a hundred years later they are no longer sent for a mere two cents, they are still collected as keepsakes and colorful collectibles.
This particular card was recently sold on eBay for $910. Yes, you read that correctly, nine hundred and ten dollars. Condition, along with being embossed (the raised printing) were major contributor's to this price. Halloween cards have always been favorites to card collectors. Add all of this to selling the item at the right time of year and you end up with what seems like an absurd price.
Cards can be found just about anywhere. I've seen them in albums, used as bookmarks and in bundles with rubber bands holding them together. They can often be purchased inexpensively at garage sales and auctions. To be successful at buying cards you need to do one important thing, look. That's right, look. It is a very simple process, when you see a group of cards being offered for sale, look at them. Don't be lazy and offer a blanket excuse that they are just a bunch of postcards that aren't worth anything. You may be passing up a golden opportunity to make a lot of money.