Best bang-for-buck purchase you have made?

For me, it was buying a pair of used Magnepan MG-12 speakers for $550.00 from a dealer in Oregon. I had heard the 1.6 before, but not the smaller 12's. These speakers have TOTALLY changed the way I listen to music - I may eventually upgrade to larger Maggies, but I think I will always keep the 12's around.

What about the rest of you?