You also have to remember that even if it's graded it doesn't mean it's a fake. Read up on the Toy Toni scandal. Original figures, bubbles and cards but not sealed at the factory. Duped both AFA and UK Graders and many a hard core collector too.
If you want to go down the MOC route you are, as already mentioned, better off doing a bit of research. Plenty of info on here and on Rebelscum.. all with collectors that are more than happy to offer help and advise. It's not something you want to jump into lightly.
** Edit.. Lom beat me to the TT mention as I was typing **