The listing fees have skyrocketed in the last year. A year ago, if I'm not wrong, Bittrex asked for 3 BTC as listing fees, when Bittrex was the number one exchange in the market. This increase in fees is due to the competition, every week many new projects are launched, many coins and tokens, and they all want to be listed and, if possible, in the most important exchanges. The exchanges take advantage of it to increase the listing fees.
Honestly, the exchange of token depends on the competition. also, the exchange of token varies over a period of so you cannot specify the exact value of each token. The most popular the token, the higher the exchange it will gain. It is true that the to increase the listing fees, they need to take advantage the exchanges of token.