For many years I have been making my own bread, mainly because I like to know that I am eating healthy bread with no preservatives, etc. I used to purchase the yeast in a glass jar that had to be refrigerated once it was opened. It recently increased to $7.29 for a 4 oz. jar. Outrageous.
If you have a recipe that calls for 1 package of yeast and you only have bulk dry yeast, this page will tell you how many teaspoons of yeast is in a packet.