I do it with beckford normally, if you can pick him up for anything under a 1k, then sell for 1k+, there is profit there, lucky for me at the moment, there is a guy trying to price fix him for 700 buy now each, called 'Los Galacticos' and I am selling them all on 1k+
Also try it with silvers, as some people are idiots and underestimate them, look for pace and dribbling mainly, any 85+ pace going cheap, check there price and try snap them up.
hope this heped you in some way