I bought one at Bed Bath and Beyond and it held pretty well to my tub surround, but after a few months, it kind of lost it's bottom suction. It still works OK as I don't hang on it, just use it for steadying. If you had to actually use it to pull yourself up, it would not be good, though.

For what it cost me, I'm happy and wouldn't mind replacing it a couple times a year. It was far cheaper than the real ones and didn't involve remodeling.