My name is Evan, I’m a Guru here with Shopify.
That's an excellent question, thank you for explaining the Oberlo costs of your product. That helps put things in perspective! Now, because this is a public forum I'm going to keep things general. Your privacy is very important so I don't want to divulge any information about your business!
Let's start by taking a look at Oberlo. Can I have you to go Apps > Oberlo > Dashboard. This is going to show us your sales and costs. If you look there you'll see that 6,31 EUR you mentioned. So the 12,51 EUR isn't coming from there. Now, Oberlo product prices do change on occasion, which can result in a decreasing margin. To prevent loss we need to tell Oberlo what to do if a price changes:
Step 1: Go to Oberlo Settings:
Step 2: Once in the Settings, choose the Store Settings at the very top.
Step 3: Scroll down to Auto Updates and take a look at When the Cost changes.
This section will allow you to decide what happens to your product price! You can also choose to have it notify you when it changes, or adjust automatically!
Now onto that 12,51 EUR you mentioned. If you're ever confused about a billing charge it's a good idea to check the Settings > Billing > All Invoices section. That gives you a detailed breakdown of all your charges. Shopify currently bills in USD so to find that 12,51 EUR, we have to convert it back:
If you have any other questions or concerns, please don't hesitate to let me know! I'll be more than happy to help!
Evan | Shopify Guru