These three links have been my favorite places to order bows. Val's is great in quality and less expensive than the other two sites. The other two sites have show bows and I love to look (I've ordered from all 3), especially at the dog form site.
Also there are several vendors on YT that offer bows, you may want to check out the for sale section.
Val's Diva Do's 5/8" x 1 1/4" Double Loops Chic Dog Bows, show leads and products for the show dog or discerning pet. Dogform.com - 7/8" Dog Bows