It depends on how you plan to sell the items. If you have a eCommerce store you are looking to sell on then it is all about content. Organic SEO through valuable content - text and video is Key.

Selling the items on Amazon and Ebay are the easiest ways. You just have the list the product with appropriate key words. You could then expand from there to an webstore after you have proof of concept and some revenue coming in.

For new niche items Amazon is the best option. For used or collectable items Ebay is the better choice.