Unless there is a literal hole rusted through it, grab some sand paper and sand the rust off of it. It's just iron. I've done it many times to rescue an old skillet or Dutch Oven.
Short of taking a sledgehammer to it, it's nigh on impossible to destroy cast iron cooking pans.
Look at Ol' Diamond Jim over there with his $100 skillets!
I got 2 cast iron frying pans, a 6qt dutch oven, a 2 burner flat iron, and one cast iron 2qt kettle. I ain't got $50 into the whole lot of them. Vintage cast iron is cheap because it will last for multiple generations and there is lots of it floating around to be had on the cheap.
And if you ain't got 5 minutes to clean a cast iron frying pan, then no $10 nuclear glow int the dark Walmart special is going to do any better in your care. I highly recommend you find someone to cook for you. Before you give yourself food poisoning.