As a pro-seller, you are saving the $0.99 per item fee charged on every item sold. If you are selling 40 items a month, this fee savings will pay for the monthly $39.99 fee. Any items sold above 40 items is basically putting another buck in your pocket. From your post, you are aware of this benefit.
With your downgrade of your account, you will not be eligible for the ‘Buy Box’. This is where a seller can have the ‘Add to Cart’ button found on the product page. As an individual seller, you are not eligible for this feature so any potential buyers would have to to go to the ‘All Other Sellers’ view to see your offer. If you currently had the ‘Buy Box’ on your listings, I would predict your sales volume would drop because of this.
As an individual seller, you will not have access to business reports and you will not be able to use inventory spreadsheets to update your listings and pricing. You will have to go item by item to update listings from your Manage Inventory view.
If you are setting your own shipping rates, this will go away and you will be given the default shipping rates for each category.
If you had to apply for approval to sell in any category you will find your listings in those categories inactive soon as all ungated categories require you to be a Pro-Seller.
If you were using any 3rd party shipping software that was utilizing Amazon’s “Marketplace Web Service (MWS)” this functionality will stop working.
There are some other minor differences, which can be reviewed from the following help page:
- [Individual and Professional Selling Plans|http://www.amazon.com/gp/help/customer/display.html/ref=help_search_1-2?ie=UTF8&nodeId=200306550&qid=1449523576&sr=1-2]