Congrats on your Avon business! I used to be a Mary Kay consultant for a couple of years so I’m familiar with the business model. In my opinion, you should go with QuickBooks Self Employed. While it does not manage inventory, it does allow you to easily track income and expenses. I think you can also benefit from the automatic mileage tracker. If you download the app on your phone, it will track the mileage to/from your customers as you deliver products. This will provide you with the info you need to take the mileage deduction on your taxes.
As far as tracking inventory, since you don’t have a lot of product I think you should set up a simple Excel spreadsheet. If your inventory gets to the point where an Excel spreadsheet is not working for you then upgrade to QuickBooks Online Plus. However, at this point I think QBSE at $17/month is much more economical than QBO Plus at $50/month.
All the Best-