Walmart offers the Evenflo High Back Big Kid Amp Booster Seat in Sprocket, model no. 31911431 for $24.88. (Amazon offers it for the same price for Prime members only.) Opt for in-store pickup to avoid the $5.97 shipping charge. That's $3 under our November mention and the lowest price we've seen. (It's the best deal now by $4.) It can convert to a backless booster seat and features adjustable height, a removable seat pad, shoulder belt positioning strap, and elastic cup holders.