2006 Saturn Vue battery- hard time staring

I bought a new battery 3 months ago. Last couple days car is having a hard time starting. Took it to where I bought battery. They checked it and said it was ok but pulling load from somewhere in the vehicle. They could not test the electrical system so recommended I take to my dealer and have the system checked out. They seem to think its something in electrical system thats draining the battery slowly. What is your opion on this before I go spending money to have the system checked. Thank you for your response.