Prices now mean that you virtually always end up saying a player "is worth XXm" but in the market their value is above that, the market dictates that sought after, in form players will be 'worth' more if their club are financially secure, because that is what they can ask for them.
Villarreal are a very small club in context though, I can understand them turning down €35m from Spurs (if it's true) in January as they had the bigger and more valuable picture to think about, but players cost less out of season and we shouldn't be going crazy for Rossi.