First of all, I'm on that side of the forum which doesn't believe that wage has any correlation with training speed. It's just market value. Also, the market seems to have changed a bit recently with newly generated (nordgens/academy) 5* 18 y.o. players being slow trainers. So I'd just suggest you buying 19-21 y.o. players who have already played games (have stats), those should be fast trainers.