eBay can be a great place to find deals, but it can also be a trap for the unwary. When looking for a deal on memory foam, keep the following in mind:

1. My own personal "favorite" scam are auctions which display a number like 4.0, 5.0, 5.5, or 6.3 but never specifically say that the number refers to a density. If the auction does not specifically state a density, do not assume these numbers refer to density. In fact, I will go so far as to say if the auction does not claim this number to be a density, then it most likely isn't. Call it a "model number."
   
   

2. Close on the heels of #1 are auctions which specify a density, but fail to specify the unit of measure. The industry standard unit is per cubic foot. If they don't specify per cubic foot, do not assume it is. Again, if they don't say, then it is probably per TWO cubic feet, which means the density is in fact HALF of what they claim.
   
   

3. I know of no manufacturers of memory foam which sell on eBay. You should investigate carefully anyone claiming to manufacture memory foam. They may "fabricate" toppers from blocks of memory foam, but it is highly unlikely that they actually manufacture the foam itself.
   
   

4. There are some quality memory foams manufactured in the USA (Foamex, Carpenter, Bergad, Hickory Springs, etal.) and Europe (Vita, Garme, etal.). I know of none coming from other continents, although of course anything is possible and I can't say for a certainty that there are none. But let me suggest this: if a company will not tell you in which country their foam is manufactured, you can be reasonably safe in assuming it's not the U.S. or Europe.