Where can you buy presidential dollar coins?

Most coin dealers sell them but banks in your area should have some at face value.

You also get them as change from postage vending machines and public transportation ticket vending machines such as train platforms ticket machines.

In addition the US Mint (www.usmint.gov) has a "direct ship" program that will let you buy the coins in bulk at no extra charge. The only downside is that you need to order 10 rolls (250 coins) at a time.