I think the main reason you don't see the lube in most of those places is that newer machines don't need the lube in the motor, and I haven't seen a lot of newer machines with gears. Mostly belts. There's not a lot of call for the Singer Lube anymore, so the big box type stores (and I'm lumping Joanne's and Fabricland (Canada) in here too) don't see enough of a market for it, and drop it. Wal-Mart used to carry it, about a year or two ago here. That's where I bought my first tube,... I think. That said, the tube lasts a LONG time. The reason I ran into trouble is that I was repairing machines. There were easily 10 machines I did gears and filled grease tubes on. If you ordered when you had 1/2 to a 1/3 of a tube left, you'd be more than fine. In the US, shipping is quick. My problem is, Sew-Classic won't ship chemicals over the border, so I need another source.
That and in the 2 weeks it takes to clear customs, even if I could get it here, I'd still be looking for an interim solution.