I agree such a transfer (well any transfer actually) is a calculated risk, and this particular one only makes sense in the best case scenario. If, however, the best case scenario is that the lad is the next Thierry Henry, the price is not too high. Player prices has doubled or tripled in the last couple of years, and I do not see why this development should stop. Pogba cost 100 million, Higuain 90 million, Watford will not set Troy Deany for 30 million. 130 million for Thierry Henry is ok for me.
Now the problem is off course that the risk is terribly high. What if he does not become Thierry Henry. It takes only a simple injury for this to happen.