OR take the unit to a professional repair shop who will even give you a warranty on their work.
We have a 3Gs IPhone that is on its 2nd battery, which was less expensive than replacing or even upgrading it.
Tablets are no different than cell phones with non-removable batteries.
Best of Luck, if you cannot find a place local let us know I can point you to one I've used for years and they seem to be based in most of the larger USA cities.
Cheers