The biggest bang for my buck has always been:
Paint the entire unit . You wouldn't think the ceilings need paint until you paint it and what a difference it makes! I use:
https://www.homedepot.com/p/BE... for the walls
https://www.homedepot.com/p/BE... for the trim and cabinets
https://www.homedepot.com/p/BE... ceilings
Replace countertops
https://www.lowes.com/pd/Stret...
Backsplash
https://www.lowes.com/pd/Anato...
https://www.lowes.com/pd/Anato...
Watch a 5 minute video about replacing outlets and switches. They're less than a dollar each and make a HUGE difference. If they don't have a ground wire, you can add one for very cheap.
Replace doot knobs
https://www.amazon.com/Bedroom...
https://www.amazon.com/Probric...
Replace cabinet hardware after paint
https://www.99centknobs.com/
Replace ceiling fans and lights. Very easy and cheap.
Replace bathroom vanity
https://www.lowes.com/pd/Proje...
Replace the kitchen and bathroom sink fixtures
Flooring is expensive and will eat up a lot of your budget. You will need tools to undercut door jambs, possibly trim the bottom of doors if the elevation is raised, install 1/4 round or shoe molding, caulk, underlayment if its not attached, floor leveling compound if you have any low spots, grinder if you have high.. its not just dropping down cheap flooring. If its not done right, it will look terrible, break apart, and need to be replaced in a year. Consider tile. The material price is very low since its out of style, but its clean and will last for decades in a bathroom and kitchen. You can watch some youtube videos, buy a leveling system from amazon, and do a great job for $1 a foot.
No one in my market has ever requested a garbage disposal and I don't think anyone would ever pay more money for one.
Lastly, I know a lot of landlords remove dishwashers. They can break or flood, but that's market dependent. I install them in my units.