I could be wrong, but I believe my father used these folks to purchase some of his roses.

Jackson & Perkins

I have ordered some from J&P in the past and was pleased with their quality. Another top-notch source is David Austin English roses. Once you have fallen in love with David Austin's roses, it will be hard for other roses to compete. They have unparalleled beauty and fragrance. Sometimes you can find a very limited selection of David Austin English Roses in local stores and nurseries, but if you want specific varieties, it is easier, I think, to order them online. Here's their website for your viewing pleasure:

David Austin English Roses

Other great online sources include Antique Rose Emporium, based in Texas, and Chamblee's Rose Nursery.

Most of the big box stores carry mostly knockouts or hybrid teas nowadays, and I usually don't shop there for roses because I like heirlooms and David Austin roses better.