Hi Joannie,
You may be able to find it in health food stores but either the price will be very high or it will be an inferior blend. Try going to eBay and doing a search for Pu-erh tea. There's a company called Yunnan that has excellent teas and they are inexpensive. The only problem is it takes about 4 to 6 weeks to get the product because it's coming from China.
You can also go to http://www.happyherbalist.com and check out his teas. He has a very good grade of Pu-erh although I don't remember what his cost is. He will also tell you which is better for all around health, the black or the green. I'm not really sure on that one, it's probably the green.