In my internet surfing I came across a store in Portland, Oregon that has an interesting idea. They custom ply yarns for their customers and sell by the pound. The store is called Yarnia and their website is http://www.yarniapdx.com/
They have a video that shows how they work with the customer and keep husbands from complaining. This could be interesting for guild projects needing just the right combo. I hope you enjoy perusing their site.