In our house we leave a leprechaun bowl on the table for a few days.
Then when everyone is home the leprechaun fills the bowl with candy. He is very sneaky.
Our Leprechaun bought the coin candy in the Target dollar section. But I have also noticed that they sell this type of candy at Cost Plus and Walgreens.
Once the bowl is out - the kids are always checking to see when it will be filled with candy. It can only be filled very quietly when everyone is home.