We don't pay high wages, and sell players on when they have a year or less on their contracts. That deflates their value.
We have done well with guys like Marvin and Erwin (and to a lesser extent, Hall) and need to continue in that mould of developing the youngsters and finding "cheap" lower league talent. Not everyone will be a gem, but it only takes one 500k deal to make it worthwhile.
The alternative is to do a Dundee Utd and tie down everyone on higher wages and 5 or 6 yr contracts, selling the occasional 1 million+ player. And we can see how that worked out.
As for Moult, we should try something creative with add-ons like 300k up front then 20k per goal for his next 3 seasons plus 25% of future transfers.