Walmart offers the Dimex Multipurpose No-Dig Landscape & Edging Project Kit for $12.53. Opt for in-store pickup to dodge the $5.99 shipping fee and cut the price to $11.98. That's the lowest price we could find by $7, outside of the mention below. It features four 4-foot sections of edging, four locking connectors, and eight 6" spiral anchoring hooks.

A close price: Amazon offers it for $12.53 with free shipping via Prime.

Update: It's now out of stock at Walmart, but Amazon still charges Prime members $12.53 with free shipping.