If you don't make bread often, you probably purchase yeast in small packets (each of three packets containing a tablespoon of yeast) from the grocery store. I've noticed that there are also small jars available; these contain about 1 cup yeast, or 16 tablespoons. Some grocery stores also carry the large packages of instant yeast which have four or more cups of yeast, or approximately 64 tablespoons. It usually takes one tablespoon of yeast for a loaf of bread in a timesaving bread machine, a little more for richer doughs.
If you're interested in saving money, don't buy any of these at the grocery store; you're paying sometimes up to 300% more than you should. Most people I know have a membership to a warehouse club such as Costco or Sam's Club, or at least have friends who do. Here are the differences in prices on yeast:
Large bag: Grocery store: $6-$8 Warehouse Club: $2.50 - $4.00
Small jar: Grocery store: $4.25+ Warehouse Club: N/A
Packets: Grocery store: $1.25+ Warehouse Club: N/A
Do the math: Purchasing packets of yeast, your tablespoon cost is a whooping 42 cents each; at $4.25 for the jar, tablespoons of yeast cost you about 27 cents each! By purchasing the large bag, you pay less than .06 each for a tablespoon of yeast. It is actually cheaper for you to purchase the large bag and throw part of it away than to purchase the jar or a three-tablespoon package of packets!
I do not advocate throwing away your yeast! Yeast will keep beautifully, even up to a year past the expiration date, if you keep it in the freezer. I purchased an airtight container from the dollar store that will hold the entire bag of yeast and will fit in the door of my freezer. I cut the expiration date off of the bag of yeast and tape it to the container, then keep it in my freezer. I always have yeast when I need it. Another way is to divide the bag up with your daughters or friends. You can test your yeast to make sure it is still good by sprinkling some in a cup of lukewarm water. If it begins to foam up in a few minutes, then it's still good.
If you purchase a timesaving automatic bread machine, you will probably use most of the yeast in your freezer before the novelty of the machine wears off (but probably not before you gain a couple of pounds from eating the delicious bread). In addition to making fabulous loaves of bread, these machines have a dough only setting, so they are perfect for mixing dough for pizza, pita bread, or dinner rolls. They consume about 10 minutes of hands-on time and do virtually all of the work for you. They can be set ahead (like in the morning before work) to finish just when you are ready for your dough or loaf of fragrant bread.
Check good-will stores if you want to try one before you purchase a new one; I recently needed more than one for a class I was teaching and found them for $5.00 each at my local Deseret Industries good-will store. I have seen new ones at discount stores for as low as $39.00.