This is cheap and works like magic I am so impressed. I found this on pintress it is not my own I do not have the link at the moment but will try to edit thw link in later.
You will need:
Vinegar
Dawn (must be dawn)
Spray bottle
Heat up vinegar in microwave for about two min. You need equal amounts I did 1/2c and it was plenty for my entire shower. So I heated up the vinegar while it was warming up I put the dawn in the bottle and then poured in the vinegar put the lid on and mixed it with a gentle shake so it did not foam up. Then spray it on the shower and the doors and let it sit for about I only had a hour but it worked great going to have to do it one more time for the tough spots but it has not ever looked this good it had a build up when we moved in. Here are some pictures of my before and afters
