In any case, if you catch a significant discrepancy which you believe evidences manipulation, then any good broker will gladly refund your investment. Secondstrade appears to be a good broker because they are willing to risk money for their 195% promotion. I wish I could say the same about all binary option brokers!
Today, a broker called me to walk through a demo of a popular binary options platform; they did manipulate the data to show that I was winning certain trades when it was clearly impossible. I was shocked! In my experience, it is important to watch out for manipulation in a demo format, but manipulation in a real trade, if discovered, will certainly destroy the broker's reputation, so it is unlikely that you will find it.
Hence, if you have an allegation of manipulation, it is your responsibility to prove it. A broker who is manipulating a data feed is not doing him/herself any favors at all, especially when the maximum bet is a mere $40 at present rates.
A trader who discovers manipulation could easily take advantage of it, and also ruin the broker's reputation.
By the way, all the major bitcoin exchange prices can be found in one place here:
http://bfxdata.com/
This page might give more accurate results, especially at night when the market is slow.
all sounds nice, but did you do some real trades with 40$ or less?