[Aer Lingus](http://www.aerlingus.com/i18n/en/htmlPopups/fees.html) has a section on overweight fee, but it lists it as a flat fee. Perhaps there is some mistake on either page.
 	
Excess baggage fees: Longhaul flights - all bags over 23kg-32kgs (50lbs-70lbs)

75 euros, or<br/>
65 British Pounds, or<br/>
100  US Dollars