Amazon cuts up to 73% off a selection of adjustable shower stools and benches, with deals starting from $13. Plus, Prime members bag free shipping on all orders. (Non-members can spend $35 or more to qualify for free shipping; otherwise it starts at $5.48; some items qualify for free shipping) That's the best sale we've seen on such items from Amazon, yielding several price lows.
A best bet is the Medline Bariatric Bath Bench without Back (pictured) for $41.65 with free shipping. That's the lowest total price we could find by $8. It features suction feet, adjustable height, and can hold up to 500-lbs.