I assume you're talking about a moral cost. But let me talk about a different part of the world first before addressing your comment.
Saudi Arabia is an outright dictatorship, more so than China (and I won't bring up anything about a source of Islamic terrorist). But the US buys oil from them. And contrary to popular belief, no one is dependent upon Middle Eastern oil. It just all depend on how much you want to spend on energy. There is currently a known energy source on the Colorado plateu that could yeild enough oil for the US in the next 100 years at current consumption. However, gas would have to remain at $5-$6 a gallon in order for it to be economicall viable to extract it. But Middle Eastern oil, only $2 a gallon is needed to pay for their oil because it is easy to extract. The only reason gas is $3 a gallon is because of the man made political turmoil in the world.
So, if you implying that America is dealing with the devil for economic gains when doing business with China, keep in mind that America has been doing that long before the current trade set up with China.
Oh, and I don't believe doing business with China is dealing with the devil :)
I know people who are very satisfied with their foreign investments as opposed to domestic ones. I understand that the bottom line to all investment is profit. I also believe a fool and his/her money soon go separate ways.