Just an idea....(assuming you meant copper)

Since there is so much metal scrapping going on, it may be hard to find copper sheets because they all end up at the scrap yard. If you go to the scrap yard and ask them, they will probably be willing to sell it to you at the price they buy it in for. At least, they do it that way here. There are all kinds of things there!

Hope you find what you are looking for!
garden_n_mom

Try your local Hardware, Building Supply, or Lumber Yard. Don't know about the thickness, but it might solve your problem. Good Luck.