Old School merching can still be done. It easier now with grand exchange because you don't have to be standing at the same spot while you constantly type the same stuf.
But it harder to fool people, by selling a little bit higher then what the actual demands is since grand exchange give people a price to actually look at.
SO back in the days, you could buy dragon boots for the actual street value of 300k and sell it for 600k if your at the right spot and have desperate enough people, making 300k profit each boots. But now you can't really fool people like that anymore.
But eaither way, merching is live and well.