It's hard to say without seeing the property but unless it's a "tear down" or real "fixer upper" whatever you cando to spruce things up and improve its appeal will likely be money well spent. The issue here may be knowing where to not cross the line. Generally, cleaning out, de-cluttering, organizing, painting, planting, and repairing can be done with a minor monitary investment and some extra time. Crossing the line may involve remodeling kitchens, bath rooms, and more major under takings.
Keep in mind that you don't have to make the home new, or change it to meet the needs of the finest tastes. What you find as offensive may be acceptable or even appealing to someone else. A fresh coat of paint can make an ugly pine panel wall often disappear.....
Consider setting a small budget and seeing what you can accomplish. You may suprise yourself!