iPad Battery Replacement

I have an iPad 1 since 2010 and was wondering how much it would roughly cost to change the battery when the time comes? All I could find is the Apple Battery page, but all it says under "iPad Owners" is that it would cost $99 under the one year warrenty. Obviously it has been quite a few years already since purchase date and so was thinking that the battery, like any other laptop battery out there, will need to be replaced sooner or later. So... I was wondering if anybody can redirect me to some information or could provide information about this topic? Thanks,