I agree with you Amazon is not the best place to get pharmaceutical products and "abuse-resistant" formulations are effectively murder targeted at the most vulnerable. They are practically eugenicist in nature.
When I was much younger I had a bit of an adventurous spirit and never had problems finding pure DXM on the shelf. The issue I ran into most often was it was a frequent target for shoplifters so the name brand gel caps would often be out of stock. Usually you could find the generic store brand version though. Delsym was almost always available. The extended release may or may not be desirable depending on how long you want to trip, but IIRC you could just mix it with something acidic like orange juice to dissolve it and make it instant release. Just anecdotal I know, but that was my experience.
When I was much younger I had a bit of an adventurous spirit and never had problems finding pure DXM on the shelf. The issue I ran into most often was it was a frequent target for shoplifters so the name brand gel caps would often be out of stock. Usually you could find the generic store brand version though. Delsym was almost always available. The extended release may or may not be desirable depending on how long you want to trip, but IIRC you could just mix it with something acidic like orange juice to dissolve it and make it instant release. Just anecdotal I know, but that was my experience.