First days of Amibay had some moderation issues. The staff was inexperienced and "over-moderated" unnecessary stuff usually. I've had my share of problems back then and got banned for some time too (it was not related to a transaction infringement). But now I see they've learned from their mistakes, and the place is run much more smoothly than in the past. I wouldn't still be there if it weren't.
As for your case magnetic, I haven't seen your 'friends' auction, so cant really comment, but generally what you got from amibay, you offer there for the same price. I've done it many times, and had no problems.