Around here, when I've done brakes, due to rust I generally just go ahead and replace the rotors. They are cheap enough. I also have used Bosch QuiteCast, and don't recall any issues with them.
Is it recommended to just replace, or possible not do anything
speaking, it is possible to not do anything, if the rotors are in exceptionally good condition. In practice, the only time I've done this is with the brakes on my motorcycle. The rotors never saw salt, and were still very smooth, so I just slapped a new set of pads on and it worked great. But none
of the cars or trucks I've worked on ever had brake rotors in a condition where that that would be a good idea. Either too much rust, or a sticky caliper caused uneven wear, or the surface was grooved, etc.
Ultimately, rotors are cheap, and at least on my vehicles it always just made sense to replace them when I was doing brakes.
If money is really tight, posting up some pictures could help determine the course of action. Otherwise, just think about how DIY is saving you tons of money in labor, buy new rotors, and carry on. Trying to save too much money can often end up costing more. Extreme example not very relevant, but I helped a buddy change the brakes on his truck cause the pads were scraping. We got the brakes off and I was puzzled, cause one side looked like it had 90% life left, while the other side was scraping. Not a sticky caliper, but the brake pad was worn at an extreme angle. The caliper piston
was ground down at an angle. The prior owner must have run the brakes so long they lost the pad entirely, and after damaging the piston, instead of rebuilding or replacing the caliper, threw a new pad on it. Not only must that have resulted in greatly reduced braking until the pad wore to the extreme angle, but again, the other pads had 90% life left. So this resulted in replacing not just pads and rotors, but a whole new caliper too (technically, we could have rebuilt it, but it's easier to save the rebuilding for a dedicated company, which is why brake calipers have core charges).
Bringing this around to something more relevant, make sure when you change the brakes to grease the caliper slide pins, and ensure it's sliding smoothly. If not, clean and grease the slide pins and/or replace the caliper, cause a sticky caliper will mean you'll be changing brake pads and rotors way
sooner than you need to, and you'll still have to deal with the caliper at that point.