2. Get preliminary estimates. Once you have a proposed floor plan in hand (and a written scope of work), most contractors interested in the job will be willing to come over and give you a ballpark estimate. The more info you have, the more accurate the ballpark number, so if you can get your designer to do a schematic electrical and lighting plan, that's even better. All of this is subject to change, but at least you have an idea of costs before you get too emotionally committed. At this point, you can also estimate material costs such as cabinetry, countertops, tile and flooring square footage and so on.