I get mine at my local Ace Hardware store but I'm sure you can get them other places also (Lowes, HomeDepot, etc)
They're made by Victor and run about $13 a pop. At any given time during a "Mole Siege", I have 8 - 10 traps set.
Be careful as these things are a bit dangerous to set. Read and heed the directions.
Moles are so cute..............when they're dead!
Rich