Removing the previous tenants that hadn't paid rent or electric in years, new floors, new vanities, new toilets, cleaning the cabinets and shower to make them look new again and repairing all electric, windows, etc.

The best idea would be to clean and re-point the bricks (if needed). 

Kitchens $15-40k (depending on finishes and size), Bathrooms ($7-10k), floors will vary but are easy to price out.

Or would they be unable to move in because you're still laying flooring and painting walls?

I am installing new laminate and it is running around $5 per square foot to remove and install old floor covering. 1500 sf x $5= $7500 just for new flooring.

Tenant is incentivized to keep the apartment clean, ready to show, grant access, etc.

He wants to buy the property himself but he says needs about 1 year to clean his credit record to get a loan.

But it needs a thorough good paint job, ripping out old carpet, putting new ones,  or scraping g hardwood floors etc.

There were a small amount of negotiations around securing tenants in the downstairs apartment at the price they identified and cleaning up some odds and ends (asbestos abatement, fire safety items, etc.)

The local price floor to buy a home is around ~$100,000.