I think this whole airport scare has been greatly overblown. Basically, fx rates in China don't vary a lot by location. In the past, hotels, banks, ATMs, and CCs were compelled to use the exact same rates. As I understand it, slight deviations from the official rates are now permitted, but the difference isn't significant (unless you're planning on spending big money over there).

The issue that gave rise to this thread was that some airport bank branches tack on y50 to all fx transactions. I'm guessing they number less than 100. Given that there are --perhaps-- 10 million other places to change money in China, it's not so difficult to avoid these service charging establishments.

While you may feel like you're a captive (of the y50 surcharge) upon arrival in PEK or PVG, you'll still be able to find sans fee fx opportunities. The fx ATMs are good, for example. And, if you walk up to the departures level in either airport, there are banks that won't hit you either.

All that having been said, your best bet (assuming you don't fancy bringing a large wad of cash) will likely be to call your local bank and ask if they have any partnerships with Chinese banks. Most banks in the US do, so I'm assuming Peruvian banks are also in the game.