would it be cheaper to get plants and flowers from a garden center or from home depot or something like that?
They're often cheaper at mass retailers like Wal Mart or Home Depot but they are often poorly cared for. They cost more at nurseries and garden centers but usually the care is excellent and you have less loss.
I have allways found cut flowers are cheeper from a nursery.
well that's a challenge cause i think walmarts have great prices on their plants and some times Lowe's offers great deals and a one year guarantee on their plants look for plants that are well taken care of make sure you check for bugs and brown or yellow leaves to get the best for your money i do not like plants from k marts cause the one by my house does not take care of them so i really don't care how cheap they are good luck and you can always purchase seeds they are cheaper than established plants or flowers
You're obviously a Brit, while I'm in the States. A garden sloping upwards from the house is a great opportunity for you to plant flowers and flowering trees and shrubs that will all be visible from the house, something you can't easily do if the ground is flat. Put the flowers near the bottom, bushes in the middle and small trees at the top, with maybe a stone path winding upwards. Under the trees, leave an open area where you could have an arch, and a table and bench with a view. Maybe also a playhouse for your child somewhere.