The model you're talking about is most profitably implemented as dropshipping. Or you could use this approach you used here, of simply selling for more than you bought for, where you also do the fulfillment. But it would save you not to have to ever touch the glasses yourself to sell them.
This isn't passive income, but you can definitely make more than with a job if you get enough consistent demand. Just make sure you don't set up a business that only has about 2 months worth of accessible demand.
The best single place I know of for learning more about this is Amazing.com
Thank you for your input, I will check out the site.