Ash here from the Shopify team. This is a great question, thank you for reaching out.
At this time, there isn't a function directly in the admin which would apply a markup to the products price based on the cost, but I have a solution which would eliminate some of the manual work! You're able to export your products from Shopify into a CSV file, which can then be opened and edited in a spreadsheet program of your choice. By setting up formulas in the CSV file, you could make the price column auto-fill with a markup based on the cost entered, or vice-versa. Once the prices and costs are updated to your preferences, you can re-import the file to your store, and select the option while importing to have the file overwrite existing products.
Before getting started with this, I suggest reading over our documentation regarding CSV files to get familiarized with how to use them. You can find our CSV documentation here in our Help Center. I also suggest exporting your initial product list twice, once to edit, and the other to keep as a backup file.
I hope this helps speed up the process of updating your products pricing, and feel free to reply back here if you need any further guidance with this.
Happy to assist! As for the difference between product views you describe, I can help clear that up! To access the product view where you can see the cost, mark up, and price, etc. for one product, head over to the Products section of the admin and click on a single product. From there you'll be able to access all of that products information, and make changes to that specific product. To access the bulk editor however, you can select multiple products from the list in your Products section, and then click "Edit products" to enter the bulk editor. We also have a handy help document here which goes over how to access and use the bulk editor for products.
I hope this helps, and feel free to reach out any time!
This is something that Vesta eCommerce can do for you in bulk as part of its automatic supplier product data solution. Check out our website www.vesta.us and contact me if you’d like to know more.