For perennials in particular,I think Walters Gardens is an excellent company.
I find their prices to be reasonable.
Before you buy, look around. What is it you are not seeing offered? Research the plants prior to purchase- to see if they are garden worthy.Easily grown, relatively diseases /pest free, long blooming, and non invasive. You don't want to grow something that will take over.
Try growing from seed your own plants. A lot of seeds really are easy to grow if you follow the directions.
Use a soilless mix to sow then after true leaves set up, then transplant and fertilize lightly.
Just some advice from one that has worked the business and is now starting my own.
Good luck.