Why do electric guitar prices change by model for same type fluctuate so much?

Anything is only worth what someone is willing to pay for it. If few people want it, the price goes down. If no one wants it, it is worthless, it is a piece of junk. But if everyone wants it, then the prices goes up accordingly. If you don't want it, don't buy it -- and the price will be lowered if everyone else thinks the price is too high.