I would like to know what paint and how to refinish a bath tub??
If you decide to hire someone (it is a big job), cheaper is not always better. Good luck.
Here's an article that might help you - https://www.diynetwork.com/how-to/skills-and-know-how/painting/tips-from-the-pros-on-painting-bathtubs-and-tile
It doesn’t stay on Home Depot sells a kit to redo it
I hope this tutorial helps! http://girlvshouseblog.blogspot.com/2015/11/rub-dub-dub-i-painted-my-pink-tub.html