Thanks for the information Jesta.

It uses value.steem.network, just because I wanted an MVP out to temporarily replace the python feed as fast as possible. Steem Value uses Poloniex+BTC-e to determine the price, and has an API I could plug into very quickly.

One of the reasons I'm able to personally trust this, is because the network doesn't exactly use a single witness as a source. One witness reporting $5 instead of $0.50 shouldn't shake the internal market.

This isn't to say it's perfectly fine for this to be a permanent solution, I will add more exchanges later on. But the network itself is capable of filtering out bad price feeds, because some witnesses update their feeds by hand, some witnesses use their own scripts, and others use a variety of the third party scripts available, like yours, @steempty's or @clayop's original.