I always shop at dollar stores for party supplies. They have good deals on paper plates, napkins, cups, plastic ware, etc. They also carry balloons, hats, invitations, and such.
If you're not too picky, go to a local party supply store and take a look in the markdown bins or sale sections. It's a good way to get party supplies at a cheaper price. You can shape the theme around what you can find.
If there's a party city in town I would suggest looking there. They have tons of different decorations for many different themes. Otherwise walmart or target.
I would check out the dollar stores in your area. They carry table supplies for parties. They also have balloons. Usually, there is an aisle for party decorations. After that, check Walmart if you can't find what you want at the dollar stores. My bet is the dollar store.
