I purchased the seeds for my perennial Baby's Breath (gypsophilia paniculata) on a Burpee seed rack at Walmart last February. Park Seeds (www.parkseed.com) has them for .95 a packet. They are easy to grow...hope this helps.
I don't know how much help this will be, but I got my perennial plants at a Lewis drug greenhouse. They have one of the nicer seasonal greenhouses here. I don't know if they are even outside of South Dakota.