You should have adjusted your Sell Prices (through corresponding Inventory records) PRIOR to creating the Fee records. Also, remember that Fees for Dues are AUTOMATICALLY created for you when you set a clubber's registration to current. Also, Fees for books are automatically created for you when you assign the book. Uniforms are about the only common thing you'd have to manually create a Fee for.
[Update: in version 5.1, fees for uniforms are automatically created using the new 'assign uniform' button located on the check-in tab or on the member's misc. tab.]
If you have not recorded any attendance yet because your club hasn't begun, it might be practical to delete all Fees for Dues and for Books since those will be recreated on the fly as you register clubbers and then assign their books. On the other hand, you could leave them and simply open each one and type over the Price of the Fee amount due. If you have already posted payments too, then you may be better off editing each Fee record to adjust the price.
Note: As regards Fees for Dues, the Inventory records do NOT affect the Price, for Dues, it is the Annual Dues Amount established for each club under Admin > Club Setup > Club Names, Logos, Dues and points.