Love this time of year when all the garden catalogs start pouring in. I've had great successes (and flops) from plants that I've ordered from mail-order sources. These catalogs provide inspiration and education.
One of my favorite sources is Bluestone Perennials. Their catalog is so full of beautiful choices. Many plants I can't find locally. The plants arrive a bit small, but most double in size quickly. And their prices are very reasonable. You can get 3 of a kind for what others charge for just one plant. I usually study their glossy catalog and then order from their online site: bluestoneperennials.com. The online catalog is also very well done and very user-friendly.
Sometimes I happen upon the same plants at the local nurseries later in the season after receiving and planting my mail-order plants. The local plants may be a bit bigger, but are also more expensive. But with the summer stock at local nurseries not available for many months, these catalog offerings are just too enticing to pass up!