Am planning on getting a powerbike

,can an xperienced powerbiker help with the following questions:
-what are the grades of powerbikes we have?i learnt there is 150cc,300cc.just explain all these to me.
-which is best?
-what are the brand new prices of each one of them(Naira)?
-what are the fairly used(tokunbo) of each one?
-where can i get one in lagos(fairly used in good working condition)?
-how affordable are the gears?
-don't mind if u give me your no/email 4 further ,
REASONABLE AND HELPFUL COMMENTS ONLY!!!
