im also currently woking, in my 6th season, i think now, and in league one, survived relegation last season and looking good for a mid table finish this year. my current CB's which i had in league 2 aswell are Sulaiman Bangura, Oliver Nicholas who i bought in my first season and Michele Fornasier. they are all young and will improve with the right training. i got them all on a free transfer at the time. but i doubt you would have to pay much for them.