Roses, Peonies and Daisies are easy to make out of gumpaste. I have never made a tulip out of gumpaste, so I don't know if it is difficult or not. There are cutters you can buy to speed up the flower making process.
If you don't think you will ever use the cutters again, then buying the flowers might be a better option. I have never ordered from this company, but they have a huge collection of flowers to purchase: