I recommend Nigeria, Ghana, those AL places...
basically, its funny cause it shows you on the 18 year old guys they are alreadya U21/ Junior national player for those countries, so makes buying really simple and easy. then thats just easy training, merchandising, etc. and once 21+ because small countries, and being trained etc. prob good enough for actual NT. so several more years of that until they are too old/replaced by better, and then. poof, TL time.