||01-20-2009 09:14 PM
You can search on line for interior door manufacturers and view their catalogues to get an idea of their stock sizes and lite configurations. Most interior doors are available in 2" increments, but that is going to vary when you start dealing with divided lite doors. Also be sure that what you see is available in the thickness to match the door you are replacing, which is typically 1 3/8" for interior doors (asumming that you are looking to replace only the door blank), as many of the blanks you see will be 1 3/4" exterior doors. Almost all the manufacturers can provide you with the names of their dealers in your area.
Ditto both previous points...they will not be cheap, and deal with a lumber yard or millwork supplier, not a big box store. The price will most likely equal or beat the big box, and you will deal with a more knowledgable sales person.