These two have lit up the Dutch league this season maybe worth a look and they are under 25 ! Cote d'Ivoire striker Bony Wilfried 15 goals in 13 games for Vitesse and an Icelandic Striker Alfred Finnbogason who plays for Heerenveen 10 goals in 7 games is 22 or 23 I think. However I believe he's just moved their this season. Further a field Bernard at Ath Minero in Brazil and Leandro Djamao are players looking to make the move to Europe in January. In Bernard's case more of a wide manbut has only just been capped by Brazil so may find it hard to get a WP. Djamao, would just cost silly money.
We missed out on this guy https://en.wikipedia.org/wiki/Bas_Dost 23, 6ft 4" scored 47 in 66 in the dutch league and got 6 in 12 in the bundesliga. £7m and would have cost us less than Zamora and Johnson and scored more than them combined.