On internet I could find many resources of how to find bestselling products but most of them talk about a niche, category or brands. I already have my niche and suppliers and I would like to know how to use websites or tools to find what exactly products are the best seller.
For example: Oakley sunglasses. I know they have very good sellers and some dont sell at all. The collection Holbrook is very famous. The black model with red lens is very popular. The white one with green lens has no sales at all. What I usually do is to check the models with more reviews on Amazon or number of sales on Ebay. It's ok but I'm wondering if I could have more resources to get better information.
Anyone could help me to improve my research?
Thanks for your time!