Most coins have no NAV (Net Asset Value) that would back their price, so to derive a fair value is incredibly hard. There are models like the one formalized by Chris Burniske (https://medium.com/@cburniske/cryptoasset-valuations-ac83479ffca7), but this is based on monetary supply theory and can only be used to derive a lower bound for the price.

I have noticed some of the new altcoins are being backed by assets like gold, charcoal, renewable energy,  oil and petroleum as they want their price to be based on their backed assets rather than just demand and supply which can be easily manipulated and it's good to see assets backed coin entering the market which might be a game changer if managed well.

The current valuations are mostly based on speculation, not the actual GDP that's being produced using them, so it gets even harder. This is why - across the field - technical analysis is what most analysts are sticking to.