The cost of a token, like any cryptocurrency, is calculated based on market supply and demand. Its value is influenced by many factors, for example, the size of the remuneration paid at the moment, the complexity of the extraction (mining) of the token. You can always find out the cost of a token in your personal account on the 'Rewards System' tab - 'Estimated Income' section. The number of tokens is limited and the mining difficulty constantly grows. Supply and demand increases the 888Tron value over time.