I am about 1/3 of the way finished a shawl for my MIL. Suddenly realized that I only have one ball and a half left so did a conversion and even though I showed the clerk the pattern (at the LYS CLOSE OUT SALE!) and how much I needed she still did not sell me enough and me being novice and all did not realize until now. AGGHHH.
Unless I am wrong here ... the pattern calls for 10 - 2oz. balls which would be 20 oz. I have 4 - 50 gm balls. I went to an online conversion site and it seems that I need 566 gm since a 50 gm ball is 1.76 oz.
Seems the yarn is discontinued. Lang Tahoma 193 color 0063 red.

You might want to call these two, and see if they can help. They've both had yarns I needed in the past, when no one else did.

www.jimmybeanswool.com

www.yarnmarket.com

there's a 'buy/sell/swap' section here - if you haven't already, you should post over there that you are looking for this yarn.

I'd also try to google the yarn by name/manufacturer and see if you can find any on-line yarn shops selling it - someone may have some in stock.

Gook luck in your search-