Pardon me for being ignorant here, but maybe I'm not the only one. In what context is "=/=" used? If it was to mean "roughly equal" I'ld have expected to see (~=). If it was "not equal" then I'ld expect "!=" or "<>". But "=/=" isn't intuitive to me.
You presume prices always equilibrate? That will not always happen. And it has little to do with trading volume. Instead, various differences between exchanges are reflected in the price. If there was zero friction between moving funds to and from exchanges, the prices would be the same. As long as there are differences, the cost (or savings) of those differences are reflected in the exchange rate.
Now a spike or drop in volume (or urgency) may cause the degree of difference between the exchanges to grow or shrink over time but generally the exchange rate will move up or down at roughly the same level between the exchanges.
As far as determining a single "current market price" for bitcoin, currently Mt. Gox must be seen as an outlier but those bids are real so it cannot be entirely dismissed. If you notice, both Coindesk's Bitcoin Price Indicator (BPI) and BItPay's exchange rate -- each computed with slightly different approaches yet seem to always land within about 1% of each other:
- http://www.coindesk.com/price/
- https://bitpay.com/bitcoin-exchange-rates