I need to buy a shower for my elderly, obese (200lbs), mother. Currently, she is able to walk with a walker, but she has really bad arthritis in one knee and it can be very difficult for her to stand from a sitting position. I am overwhelmed by too many choices on the internet and have no idea what to get for her. I'm also frustrated by the prices. Any recommendation for a suitable chair at a reasonable price (less than $100) would be appreciated.