The best cheap strikers on the game for me are Leonard Kweuke and Yannick N'Djeng. I will add Ademilson to them since he is not that expensive if you buy him early on.
But for me the best striker here is Cavani. Absolute beast, his overall contribution to the game is absolutely great (scoring...
I would recommend using 3-1-3-2-1 but i don't know if would work for you since it is not very common (as far as i know). I used it very little on my save and i cannot say if it will work for you. All i did on my save with this tactic is setting my DM and the MC in front of him on defend plus...