My recommendation would be to look at other properties in the price range you're hoping to sell yours for. And be brutally frank with yourself. Is the current condition of your home as good as those other properties? If the answer is no, then do the updates.
The benefit of updates in a buyers market is that your property would presumably go to the top of the list based on desirability. This is an important concern if you are looking to sell quickly.
I wouldn't be concerned with generating a higher sale price for the upgrades. Rather, if you can get your investment back and get your property sold quicker, then the upgrades are still a good investment.
This may mean simply changing some light fixtures. If the house is dated, you pay for it with a reduced price you will get for your home.
The cost of your repairs will 9/10 be less than the money you would loose in negotiation and the effect will be priceless. If you think it needs improving then your buyer definately will.
I would interview a couple of Realtors to get their perspective and recommendations in your particular market. There is no charge for this and you'll feel better about the decision you ultimately arrive at.
Good luck to you Sue.