A Google Sheets or Excel File that you cand play with to see how your prices, Cost of Good Sold and Number of Customers are stacking up.  
 
Here's how I do my personal budget:
https://www.tinychickpottery.com/product-page/digital-kakeibo-for-the-spreadsheet-savvy
 
Here was the related Facebook Post on the topic.  Enjoy!
 
Pottery as a Business
 
Sometimes we potters focus on what we want to do and don't spend enough time working the numbers to see if our businesses are sustainable, financially.
In a former career, I made a lot of spreadsheets. Recently, I made a spreadsheet using (free) Google Sheets to figure out my gross profit margin (GPM) on hosting pottery glazing sessions. As a service based business my GPM "should" be a least 80% so my business can afford to grow, advertise and get more business.
If I wanted to continue teaching classes:
charge more per student.
reduce my cost of materials by buying gallon sizes of glazes
For more profitability
Larger groups of students
Skip the middle man and buy from manufacturer
I tested recently offering a ladies night at $35 which is not sustainable but really fun... and a daytime by appointment class at $55.
A few grumpy people online told me $35 was too much, so I was so surprised to find that plenty of people thought the price was too low for this particular offering and were happy to pay $20 more.
Make the value higher by making people feel special
Place cards and a selection of teas and sometimes espressos.
Put out goodie bags.
Set the table like it's a party.
Add mood lighting at the beginning of class to make it a special occasion.
Here's the Cost of Goods sold calculation. Set cell to display %.
=SUM(C4-G4)/C4
( (COGS cost of goods sold minus total income) divided by total income. )
 
If you have corrections or have other useful calculations to add that we can share with the group I'm happy to update this to update and share that information, also.  Just run it through the shopping cart and your total will be $0.  It won't ask for payment.  You'll get the file in email.  
 
This was just a file for my use and I hope you enjoy it.  I'm not currently a financial advisor or finacial professional so use your own due diligence before makiing changes based on what some random internet person (me) says.  : )