I am a shop for value kind of guy so I usually won't pay full retail price for anything unless I just have to have it. You might consider joining a plant Coop. You can get most plants at wholesale prices. Do a search online for "BnP Plant Buying Coop". I am a member of it and have bought around 100 varieties of tissue cultures hostas through it plus other things for a fraction of the cost that others pay. They hold coops all year for all types of perennials and sometimes tropicals. You can even get certain things before they go to market. One of the ladies that runs the coop is Woodthrush here on GW. She usually hangs out in the hosta forum, especially the hosta exchanges part.

Local fundraiser plant sales are a great deal as long as you research how invasive the stuff is before you plant it.

There are a few garden group sales in towns around here where the plants are $3 to $5 and you know they are going to work in your zone. Ask you local master gardener group for the places to hit this spring.

I have gotten some lovely shrubs etc for $3 to $5 :)

I have been in that coop that was mentioned. I'm not anymore.

I live in the St. Louis area and I use Craigslist. I just do a search for plants and have found a lot of local people who grow and sell their own plants for a fraction of the cost. I have also found out about local garden club sales and people selling plants at local farmers markets all on Craigslist! I check it every couple of days, you usually see more post near the weekends.