Not sure if you mean something different than this with the term "fresh" yeast. If you refer to fresh active dry yeast, then here's my suggestion:
I get mine online from bulkfoods.com.
Here's a link to the page that has yeast included on it:
I bought a pound of it for $6.00 more than a year ago and keep a small jar of it in the refrigerator with the bulk of it in the freezer. I still have about half a pound remaining and it is still as active as when I first purchased it.
You'll also find active dry yeast in most super markets in the baking and spices aisle. The common brand to look for is Red Star or Fleischman's.