Redirecting product on product page

Site URL: http://www.michaelluckemusic.com

Hi, I'm new to Squarespace and trying to get a Store set up the way I want it. I sell sheet music, but due to copyright issues, several of my items are sold on another site. However, I would like to have all of my items grouped together in the same space, regardless if they are being sold directly by me, or not. Here is a link to my store page - https://www.michaelluckemusic.com/store. I currently have it set up so that the items directly underneath the "Transcriptions (Published)" banner are contained in a few List sections, and the images are clickable to pages that I created by hand, kind of mimicking the Portfolio style. Underneath those lists is currently my only product being sold directly by me, the Tal Cohen sheet music. 

I'm wondering if there is a way that I could enter all of my items as Products on this page so that I will be able to sort them easily, and make use of Tags and Categories. The problem is that those items of mine that are being sold on another site should have a different looking Product page. One without an "Add to Cart" button and a link to the item in the store on the other site.

Any ideas would be greatly appreciated, and even a completely different approach might work. Thanks!

I would be to make a product for each one, and hide the add to cart button on the ones you don't sell directly.

You can then add in a link to the other site, and even make that link look like the add to cart button, have the text be "buy now at ____" or something similar.

I think that would be the only way to search and categorize them with the other products.