I was recently referred to a book on the winds in Gaelic culture after my inquiry here earlier this year, and looked up a copy online. I found one for $20 used, and got it in the mail today.
The Twelve Winds of the Ancient Gaelic World by Jean Wright-Popescul was written by a native of Cape Breton. The book consists of about 75 pages of sources on the winds and their colors with her personal speculations, and another 110 pages or so of folk tales retold from the Gaelic-speaking world.
Ms. Wright-Popescul is careful to cite her sources when she speaks of the historical documents, and refers to a good number of excellent sources and Gaelic-language materials. I took most of the uncited statements as her personal ponderings on the topic of the winds and colors, and found a good deal of use in it. The book is quite nicely done, and contains a color plate of the winds with their Gaelic color names in the appropriate direction.
As a student of the ogam, which includes the color ogam, this book has been interesting and useful, worth the $20 I paid for it. That said, there are copies out there averaging $40 to $50, and I think paying $40 would probably be a bit much for the information, but it does collect information from the Saltair na Rann and the Brehon Laws regarding the winds and their qualities and colors that would be difficult to come by without a sizeable university research library. Her endnotes provide the Gaelic where her text proffers English, and her select bibliography offers a wide variety of Celtic scholarship.
I could have done with a little more wind/color information, assuming it existed, and a little less retelling of folktales, but I'll give this one four purple winds out of five.