The USCIS site also has for calculating form filing fees. If a form has a flat fee, you can see that flat fee by simply selecting the form from a dropdown menu. If the form has a variable fee, you answer some questions to calculate your fee, after selecting your phone from the menu. The site also has an early filing calculator for the naturalization application: N-400.
Another facility available through the USCIS site is the online filing of applications. You can file many forms online including the N-400, I-90, I-539, N-600, N-600K, etc. For more information on online filing, visit the following section.