I go middle of the road parts from my local parts store, Brakebest (O'Reilly's), Carquest (Advance Auto), Duralast (Autozone), etc. Whoever has them cheaper.
Lots of vehicles have remote batteries. It's not that difficult to access, turn the wheel to the right and remove the access cover. Clock spring has been identified as a possible culprit for the alarm issue. It's 15-year-old vehicle. There's going to be some maintenance costs associated with a vehicle of that age. Welcome to the forum.