Need an approximate cost for replacing electrical wiring in old home.?

We are looking to buy a 1938 home (foreclosure) approx 2350 sq feet and it is in need of repair. One of which is replacing all the electrical wiring throughout the home. We got one estimate which I though was very high (15-20 grand) and want some ideas of what a good estimate would be. It has 1& 1/2 stories. Let me know what you guys think so I'll kinda know what to expect. We are in the process of getting other estimates.