More the volume of transaction the higher the price of crypto.

And good example is bitcoin,you see bitcoin is the crypto that have the highest volume of transaction that why it's the most valuable crypto.

These are exactly like stock market, instead of ipo we got ico which is initial coin offering. The prices are decided by buyers and sellers. The exchange where the coins are bought or sold ( poloniex) reflect the same prices only.. The future is going to be good for cryptocurrency and next 5 years there will be millionaires.