Toys"R"Us offers the Little Tikes High Back Toddler Swing, model no. 637247C, for $19.99 with free shipping. (Amazon charges the same shipped for Prime members; Sears has it at this price via pickup.) That's the lowest total price we could find by $5. It features an adjustable seatbelt and wide seat and leg openings, and includes hardware and cords. It's recommended for children ages 9 months to 3 years.

Update: It's now sold out at Toys "R" Us; however, Amazon and Sears still offer it for the same price as mentioned above.