Bathrooms are easily made beautiful on a budget since they are relatively small areas. Clear out all of the expired beauty products and give the room a really good cleaning. Paint the walls to brighten things up. Buy a new shower curtain and sew up a pretty curtain for the window. Relace the cabinet knobs. You are more than halfway there!
I love the look of the hurricane globe with a candle in it as in the picture above! Add a pretty soap holder and decorative jars to hold cotton balls and perhaps decorative soaps found at the dollar store.
Baskets can hold rolled bath towels if you haven't a linen closet (see the picture above). A nice plant would be nice and it would thrive with all the moisture and humidity. You can use pretty zippered bags or baskets to organize beauty and haircare products stored out of view.
Try making your own homemade bath potions, buy an inflatable bath pillow, light a scented candle and turn on your shower radio when you need a little extra self-care. Invest in fluffy towels and wash cloths.
You can create your own spa at home for very little money. Beauty doesn't have to cost a fortune!