A cousin used little pots of African violets for the tables, then told everyone to take some home. That's cheap, and they looked good. Maybe hit a garden centre and check out what's on sale/order up something for the date?
I used plastic flowers.. rented them along with the plastic 'cake'. They do some amazing stuff with plastic. I was opposed to the idea until I saw prices for real cakes and flowers.. and they really did look fine.
(Dad made real cheesecake for dessert.)
Those paper roses look fantastic, but also like waaaay too much work for me.