It does really depend on the other comparable sales. You can't see electrical and plumbing so they don't make a huge difference if they are the only things done. With that said they are great things to do. A $600 dollar dishwasher only makes sense if the stove and the refrigerator are also up to par. $300 in cabinet changes is miniscule. If you have thousands of dollars worth in appliances the cabinets better hold up to them.
And like Patrick said, if the other homes are selling for $300,000 no matter what you do you won't ever be able to make your house sell for $350,000. However it can go the other direction. If all the homes have granite counters and updated appliances and they are selling for $300,000, well you better have those thing if you want to sell for $300,000.
Along with kitchens and bathrooms, new windows are incredibly important in selling a house.
Personal Real Estate Consultant
I have purchase-remodeled and resold over 50 homes. I have a very good eye for resale-and I always preview the competition (homes for sale in your surrounding area).
Let me know if you would like me to see your home and assist you in deciding what will bring the house value and what a potential Buyer would want. No obligations what-so-ever, would like to see what your thinking about doing.
Baths are a great investment. floor coverings and paint dont usually increase value but help sell faster in my opinion.