amazon.com has this Nisaku Namibagata Hori Weeding & Digging Knife for $9.97 with free Prime shipping.

• This knife has both serrated and straight edge blades, and can be used for gardening, landscaping, and as a camping tool.
• Hangs neatly on your peg rack for a tidy shed or work bench.
• Inch markings on the Japanese stainless steel blade will ensure your plants and bulbs are planted at just the right depth.
• The Nisaku blade is rust-proof and scratch resistant.