I just looked at the KS clematis, they're beautiful.
I got my first few clematis from Bluestone Perennials years ago, but the majority of my clematis come from Brushwood Nursery. They send beautiful plants that do really well here, and it's wonderful that they're located less than 2 hours from where I live, so that helps with shipping charges.
Kayleigh, I forgot to mention that I mulch my clematis with pine straw. It gets so hot here in the summer time, I'd be concerned that rocks at the base of my plants would cook the roots. They're so many other plants in the peony beds, that the foliage also helps to protect the roots of the clematis.