Where can I find Silk or Satin sheets for my XL Twin Size dorm mattress? HELP!!?

I am moving to a dorm in January and I am looking for silk or satin sheets for my bed but I can not seem to find any anywhere so if you know where I can get them please let me know.... Its an XL Twin mattress too! Much thanks.

wal-mart had them on sale two days ago. the 200 & 500 thread a set was 22.00 dollars. maybe they are steal on sale.