I'm with Schwab. They don't have a "total market" fund like Vanguard does, so I did invest into one of their "emerging markets" ETF (based on:
http://www.bogleheads.org/wiki/Three-fund_portfolio#cite_note-9 ). I'm down 23% so far (i.e. the value is now 77% of what I've invested. Not down 23% since "all time high").
Following the "buy low, sell high" rule of rebalancing, I will actually buy more of that some time soon. I'm following my plan. From my perspective, looking at P/E, etc... is trying to do what fund managers do, "playing" the market. I'd rather stupidly follow my target portfolio.
Now, if you're already with a "total market" fund or ETF, there's probably no good reason for you to look into China. You already have some of it in your portfolio at this point.