I also suggest the big sets that come with 4 packages - so the Classic Ovals come with large scallop ovals, small scallop ovals, large plain ovals and small plain ovals.
The best place to buy the complete sets, IMO, is
Scrapbooking Alley. Free shipping, no sales tax.
Right now
Scrap-Mart is having an awesome Nesties sale, if you are wanting individual packages it is $13.99!! And free shipping, any size order, when it is dies.