I have been introduced to a few co-ops either for fabric of for yarn. I just put in an order for Mosaic Moon Yarn and now they're offering a Purewool co-op. I think I'm forming a dangerous addiction for hand dyed yarn. :)
So in the near future (after the Holidays) my YYMH option might expand to offering size customs on specific colorways for Longies/Other Crochet items.
Here are the colorways I'll be working with, either for myself or a pre-order for longies, from Mosaic Moon (pics from Mosaic Moon's website):