You DON'T separate a shower from a bath that is in need of reno on no resources.You stay in one thread, as you began, it is the same bath.

If you have literally "No resources" nothing is affordable!

Rust, means too much humidity, not enough ventilation, and it's rather pointless to do anything until that is corrected.

Limescale is hard water, and a lack of due diligence with daily maintenance of clean/wipe and DRY, so that soap and hard water don't cling and create the issue.

Replace your faucets, lights, paint the vanity and walls .....and call it a day until you save money. Get a FAN, and leave the door ajar after every shower while you run the fan.

If the shower has mold and lime scale, but no leak? All this must be addressed , as above and may mean you need a water softener installed, along with better ventilation

Lime scale remover does wonders for fixtures that have not had much care over the years. I personally would add an area rug and some nice towels. If you want to make changes after saving up some money I would do these in order of.....replace the faucets, sinks and countertop removing that tile backsplash, change out the double lights with single ones over each sink as the double look very crowded. Maybe someone will stop by and do an AI generated update for you.

Please show close-ups of the limescale on the lights and faucets. Limescale on lights would be very unusual. Are you in a tropical area?

CLR is a good limescale remover for faucets. Follow up with a generous coat of neutral shoe polish, as Moen recommends for their faucets.

What products have you tried to remove the rust and lime.

I'm confused that you have no budget but are looking for affordable modifications. That seems a contradiction to me. Are you looking to replace your faucet and light fixtures and are asking about inexpensive ones? Please clarify.

How many people are in your household and would you feel comfortable showering with the door open so the steam can escape? And taking shorter showers, and wiping down the walls afterwards?

We have a condo with a ventilation issue that we are unable to remedy. We take short showers with the door open and place in the room little Damp Rid containers. It is amazing how much moisture they capture. These are just band-aids. Not a real solution. But, as I said, we can't actually solve the problem.

Based on my own experience,

Different ways it could be done

- deep scale clean,

- diy, sanding, spay paint (Pintrest)

- amazon, Walmart, habitat humanity

- minimize budget & save

Is the shower to the right side in the photo? Is it part of the vanity section, or is there a divider? I know you said shower is seperate issue. But I'm thinking on your fan action. Might not be so necessary in the vanity area if it is seperate from the shower. But always make sure your bathroom fan is working well and sufficent for your bathroom space. If it's outdated or puny, I would replace that first. Get some CLR and clean up the fixtures before thinking of buying. Note that you have buildup- do you have a water softener? Is it working and filled with salt? If you don't have one and can get one, I would do that next after the bathroom fan. It's pricey, but that hard water goes through the whole house.

A couple gallons of primer and paint and the stuff to use it with is usually fairly inexpensive. Depends on the paint you pick, some of it can get pretty expensive. But often rehab stores have paint too.

Deep clean it. Put your stuff in there. Towels, rug. Maybe a little stool or bench on the left there if there is room and desire for it.

I agree with Jan to a point . IMO the lights and towel bar and the tower all need to go . There are many inexpensive items to replace those with. Try amazon for sure even for the faucets. I do need to see exactly the issues with the finish but those lights are all wrong so might as well bite the bullet. If the issue is moisture in the space that IMO has to be dealt with NOW it will not get better.. simplynatural has some good ideas if you can save all that stuff.. The shower is another issue but please do not start another post when you are ready to show us that .