Buying plants is pricey. I love to going to the nursery and drool over all the plants I want. It gives me ideas of what I like and how I can get it cheaper. I hit sales when I can and hold out if I know I can buy it cheaper else where.
Another great way to save money is to divide perennial plants when you can. Your plants may be smaller for a year or two than had bought them but who cares. Think of the money you're saved.
Also share plants with friends or neighbours when you are doing your dividing. I have baby Hosta that I got from my neighbour's Hosta last year. It is still growing in a pot as I need to find a special home for it this summer (I am planning a shade garden). I have an Aunt who is a gardening goddess. Her garden is AMAZING. She has given me many plants over the years that she created when dividing her plants. Some that she gave me last year I have already been able to divide again!
I look forward to being able to share some of mine in the years to come as I build up my stock. Not only are these divided and gifted plants free but they hold more meaning. They each tell a story and give you good vibes as you walk around enjoying your garden.
Dividing is a new thing to me. I've always been scared of killing the plant. A couple years ago I started with Day Lilys and went from there. I divide my plants very early in the spring when they are just coming up. As far as I know this is the best time to divide all perenials. This year I divided a fern, and some asters (both from my Aunt last year). I also divided my sedum for the second time. I took one baby from it last year and past that over to my sister. I took four more babies from it this year.
Above is the Sedum. It gets bunches of bright pink flowers in late summer. A large sedum was here when we bought the house 5 years ago. It has doubled in size now even though I have taken five babies from it. I have planted one of the babies, gave one to my sister last year, another two are for a drought tolerate garden I am planning. The fifth is going to my neighbour that I got my baby Hosta from (though she doesn't know it yet...ssssshhh).
Also in the picture is one of the divided Day Lilies from last year.

This is a divided Day Lily and the baby Hosta I got from my neighbour's Hosta last year. These will be going into a shade garden I'm planning.
All of these perennials are divided in a very easy manor. Dig around the roots and pull away a chuck of the plant, leaving both parts with a good root system. Get roots back into dirt and water right away to avoid the roots drying out.
So go out and divide, share and trade!