Dan, if the quality of the pen is as good as it looks in the picture I don't think that you will have any problems in selling these.
I did not have a clue about IPG Nibs until this post came up. I just assumed that because the nib said Iridium Germany, when anyone asked me about the nib I just told them it was a "German Iridium" as it says on the tin. I will now have to change my sales pitch but of all the Fountain Pens that I have sold with these nibs I have never had a complaint or one returned with a faulty nib.
I think it's just a case of speaking to your supplier to establish the true origin of the nibs so that when we come to sell the finished item on we do not mislead the buyers.
Vic