I was playing around with the idea of flipping flasks. On Sunday before raid peak time I had a look at flasks of endless rage. There were 29 on the AH at the time going for 22-24g listed as singles. I decided to buy them all out and relist them in stacks of 4 (and one stack of 5) at 32g each as an experiment.
My thinking is that any decent raid is going to run for about 4 hours, so by not giving them a choice to buy a single, raiders had to buy a stack of 4 (and paying more for each as they had no choice). This collapsed the number of auctions for flasks from 29 down to 7, effectively reducing the supply in terms of individual auctions and reducing the chance to be undercut.
I believed that the chance of someone buying the stack, splitting it up and reselling them would also be low as you wouldn't buy an overpriced stack, split it up and try and sell it for even more.
I sold all seven stacks within an hour and a half and I'm keen to retest this theory again, maybe Wednesday.
I guess, if you can't find a vending machine for a single can, you have to pay for the case!