Wouldn't "scalper" be the right term? I've always thought "flippers" referred to people who find things cheap and then fix them up, or do anything that adds value, to sell them for a profit. For example, buying a trashy house, an antique cabinet, or a filthy pinball machine for cheap, fixing it up, and then selling it to make a profit.
Scalpers are the people who, knowing that there will be a lot of demand, just buy things with the intention of reducing supply and re-selling them for a profit even though they haven't actually done anything to increase their value.
Maybe the words are interchangeable but I've always felt "flipper" was a more positive version of the concept.