I also use coinmarketcap to know the coin price, it is just a benchmark and can not be used as a reference. The actual price is the price that is on Exchange.
Coinmarketcap is a huge reference and a huge tool for new tokens to be promoted in there, i do not see why we shouldn't use it. But the price is an average of all the exchanges in where X token/coin is listed on. it is not the real price.
I use coinmarketcap, but double check the bitcoin price directly through bitstamp's API using this link.