I don't know about you, but I'm finding it difficult to locate an actual 8GB microSD card these days in brick-and-mortar stores.
There was a time recently when I could buy either 4GB or 8GB varieties somewhere in the $7 or less price range. Now at Fry's Electronics today, the 16GB cards are about $4.99 at the low end and none of the pegs for the lower-capacity adapters have any product whatsoever.
I spoke with the guy who runs "the cage" of spill-over products there and he really didn't seem to understand the need for lower-capacity cards like this. I educated him a bit so maybe he could make different buying decisions in the future. He seemed to suggest that the manufacturers themselves aren't shipping them anymore; they've had an open order to refill these but the product just doesn't arrive.
I just bought eight more of the cards direct from the manufacturer's website just now but I thought I'd throw this out there that you might want to stock up if you're seeing the same trend. The bigger cards in theory would be a better deal but the reality is that if you're publishing an ISO then you want the least worries for yourself and the person who later downloads it. Yes, there are ways of shrinking the second partition but I consider my time into the activity; I'd rather not go there.