A lot would depend on how easy it was to re plumb the house. If it's a single story house with exposed basement or crawlspace, it's a lot easier to re plumb than it would a multi story home or a home where the basement ceiling isn't exposed.
One way to save money would be to switch to pex plumbing (assuming your local building code allows it). The cost of copper has gone way up, plus pex is easier to install than copper as it doesn't require solder joints.
Well there are several factors that can determine your price such as are you replacing it with copper or more of what they are using today which is pvc. Replacing your whole home can be expensive. You may want to start with what needs to be replaced. There is a helful site I go to for costs which is below. In the upper right type in replacing copper pipes cost and it will give an roundabout estimate. Otherwise, if you are really moving forward have about three plumbing contactors come out to give you an estimate. They typically dont charge for estimates as they want your business.