From the Super Mario Wiki
Blappy is a seventy-two-year-old Blobule and the 'elder' of Planet Blobule. The heroes meet him at the end of Chapter 4-2, at which point he explains that he spent his life searching for the 'big treasure of space', before offering to sell them the Ancient Clue he was able to acquire for 1,000 Coins. He does, however, lower the price to 100 and ultimately 10 coins if the player declines the offer, which must be done at least once due to the maximum coin capacity of 999. However, if the player refuses Blappy's 10 coins offer, he will put the price back at 100 and will refuse to go lower. The Ancient Clue Blappy then gives to them serves a dual purpose - in addition to providing a hint as to the location of the shortcut to the Whoa Zone, it also must be given to Fleep, who proceeds to use it as toilet paper, exits the outhouse he was locked within, and joins the player's team.
Tippi describes Blappy as 'greedy' in her Tattle of him; she claims that he sells clues that he copies down from space relics.