how about in crypts who regulating the price of the altcoins in the market?
There's no one that regulates the price of altcoins but the well known game is that it is "manipulated" by the whales.
Who set the ceiling price of the altcoins?
Its basing on the total supply in circulation and market cap so do the math.
Who tell that this particular coins are worth of this?
Investors and anybody who is believing that coin is good for investing so its an open discussion to tell if this or that coin is worth of that price or worth to invest and hold.