I see it over and over again. Home maintenance items that are not taken care of for years costing sellers thousands when it is time to sell. One of the biggest ones I see is windows. The paint starts to wear off of the window sills and the corners of the window - especially on the west side of the house where the sun is strongest. If you catch this immediately and put some primer on the window, then paint it, that takes care of the problem. If you let it go, the window sill rots and soon you have to replace the whole window. If it is a special order window, it can cost thousands.
Another issue is door sills. This is so simple - the sills need to be caulked or water gets up under the floor. This is especially a problem where you don't have an overhang over the door and the water hits the door and runs down. It is a problem for the doorframe as well. Keep the sill caulked, the door primed and painted or you will see the floor on the other side (the inside) of the floor rots from underneath. Then you need to replace both the subfloor, sometimes the sill plate that runs around the foundation AND the floor.
These are just a couple of items to look for. Don't know if you have a problem; call a home inspector and have him check out your house. They go through a checklist and write up items they see that have already failed and items that you need to watch out for.
Since I am a relator in Hoover, Alabama, I have worked with several and can give you some names. Remember a few hundred dollars spent today can save you thousands down the road. Contact me at www.ToniBird.com with any questions.