Bitcoin prices vary depending on the exchange they're trading on.

For instance, as of 10:50 a.m. ET on Tuesday, Bitcoin was trading on these exchanges at the following price points:

Kraken - $17,212

GDAX - $17,150

Gemini - $17,039

Bitfinex - $16,957

Bitstamp - $16,979

The varying prices come down to a few things.

First, liquidity. Bitcoin trading volume can be massive on the larger exchanges, such as the ones above, but much lower on smaller exchanges. Those differences in supply affect the price.

Second, there's no established common way to price bitcoin, which means nobody knows what it's "supposed" to cost, and the price is based purely on trading.

Third, moving money across exchanges can be messy and inefficient, and requires lots of collateral to do efficiently. That means it's hard for traders to arbitrage differences across exchanges, which allows these price differences to persist for longer than they would in a more efficient market.

Finally, Pisani says there's an "infrastructure issue" wherein buyers can't currently quickly buy bitcoin across multiple exchanges at once, again, making it hard to arbitrage these price differences. Pisani says this will be something that needs to be looked into during the next year as bitcoin increases in popularity.