Fair value's site is here https://www.coinfairvalue.com/. You can clearly see good coins like BCH and Dash are undervalued by exchange pricing. BCH is actually worth ~$710.93
That website is junk. Just a couple of months ago the fair value for BCH was over 1500. Fair value is what someone will pay for it, which right now is 297.
That doesn't make any sense. That's like saying CMC is junk because BTC's price used to be 20k. Fair value is what I said, what you said is MARKET value. They're not the same.
Usually but cryptocurrencies give us down to the block time-level accuracy on transaction use which trumps exchange price. B/c that's just a guess since ex trades are almost all off