One of my all-time favorite television shows as a child was $ale of the Century. It was a simple question-and-answer game show with a twist: All correct answers only awarded contestants with $5. However, at various points in the show, contestants would be given the chance to buy thousands of dollars worth of prizes for next to nothing -- a new recliner for $8, a trip to Hawaii for $17.
It was a special economy all its own. A trip to Hawaii could cost $2,176 in one place while costing $17 in another. It's the same good ol' U.S. currency -- it's just that $17 has a far greater value in one context than $2,176 has in another.
Like said game, the patch 4.3 PTR operates by a bizarre set of economic rules all its own, if you can even call them rules. It's the wild west of economies. Anything goes. The fantastic BOE Mekgineer's Chopper is normally valued at 15,000 gold. But today, on Sale of the Azerothian Century, that Chopper can be yours for only ... 1 silver. Or 240,000 gold. Depends on who your seller is.