Montblanc 320 Replacement Nibs

[Valdair]

I bought a used 320 in pretty solid condition from someone on the Pen_Swap subreddit, but it has a steel nib and its gold plating is missing. The nib is okay but not great. Ebay has a few 320 nib+feed units listed (if you search "Montblanc 320 parts" you'll get about five hits) and while they all look more or less correct based on images I can find of the real thing (I have not yet found out how to disassemble the section of the 320 safely) they are all from Thailand and mostly listed as 18K rather than the 14K I'm more familiar with in the 22X and 32X pens. I'm assuming the "White Gold" nibs are just steel with "750" printed on them. Is there a reasonable way to get a replacement nib without just buying another pen? I've been keeping an eye on listings for the last week or so and nothing being sold as "parts" seems remotely legitimate.

 

Pen in question:

http://i.imgur.com/cIYC4w5.jpg