If you are looking for a really good coat for your Yorkie this is what I have for all 3 of mine and they are really nice looking, warm and seem to be good quality as well at a reasonable price.
5294 New York Dog Aspen Suede Coat | eBay
I am not affiliated with this seller but I have ordered from them in the past as I have 3 of these coats, one in each color for each of my Yorkies and have also ordered dog beds from them as well.
I absolutely love the coats. They feel very nice and look amazing. Just wanted to share what I had found as I think the price is really good for the quality of the item.