Hey, it seems like some people have trouble finding this (I did). I know you can order it online, but sometimes you need it NOW!
Just an FYI, I looked it up on Gunk's web site and there are a variety of distributors...but many of them don't seem to actually carry it (My Home Depot didn't). One place that has definitely had it for me is O'Reilly Auto Parts. I called 3 local shops and they all had some in stock. So that's a place you can try if you're having trouble.
They also list Farm and Fleet, and Ace Hardware. I didn't try Farm and Fleet, but 2 Ace Hardwares in town didn't have any.
Good luck all! (heh, I don't even have my machine yet and I'm hauling all over town trying to find lube for it. I need help).