You put your home up for sale. An offer came in, you got excited, and you accepted the offer!
Then, the buyers had a home inspection done. The buyers asked for a few repairs. You (the seller) agreed to do the repairs.
Instead of hiring a professional, you did the repairs yourself.
Think this through very carefully. Why would you want to do the repairs yourself? If you think you will save some money, think again. There is nothing worse than doing some repairs yourself, and then after the closing, the buyer moves in and finds the work you did was not correct or up to code! This can lead to a whole mess of issues. Should the buyer re-inspect the work done before closing? Sure. Does that always happen? Not always.
Could it cost more to hire a licensed professional? Yes, it sure can. But, please look at the bigger picture: By hiring a professional and getting a paid receipt for work done, you are taking some of that liability off yourself. You are giving the buyer a paid receipt, showing no money is owed. The receipt then shows that a professional (they should be licensed where needed, bonded and insured) that has corrected the issue. If the buyer has any issues, or if the item in question is faulty or breaks down the road, they can refer back to the professional and show proof of work done with the receipt. You have taken measures to hire a quality professional and paid in full. Some repairs may come with a guarantee or warranty, too, where as if you do the repair yourself, you wouldn't be able to provide that extra feeling of security to the buyer.