How do I find the right paint to cover up this hole in the wall?

Hi all, recently, I had made a hole in the wall and I have patched it up with spackel and have sanded it down and it looks great. Its only about a size of a nickel but my problem is painting over the hole. The walls in my room are an off white, but how do I go about finding the correct shade? Do I have to buy a big gallon of paint?