Don't be too alarmed, his marketvalue rises progressively with his skill lvl. As long as they're not older then 21 years, they'll be on their seasonsends MV soon enough. If you keep training them this season as you did last season they'll surpass it easily. At age 22 their training capabilities drop, so if you want to save money, sell the 21 year olds in the last week of the season.

There's no way of knowing, but the team you start with can be pure gold. If you pay little effort in your young talents they'll be good to win the first 2 seasons. You might end up in tough leagues and cups if you push your quality to the max.