How much does it cost to fix a broken window seal?

If it is a vent window (the part of the window that slides) prices aren't too bad. You can remove it and take it to a local glass shop. Prices can range from $30 up. Completely depends on the type of glass, size, and style. If it isn't a vent window a professional installer will need to come out to remove it. So at this point the price goes wildly up. So you'll be adding the installer's labor to the cost of the window repair. Expect double to triple the cost of being able to take the vent window in yourself.