I'm not expert, but what wallawe says makes sense. So the next step/question is, what can you do, that ebay and cl already do, but an order of magnitude better

I'm not expert, but what wallawe says makes sense. So the next step/question is, what can you do, that ebay and cl already do, but an order of magnitude better. What pain do ebay or cl users experience that they would pay to make go away. Alternatively, what can you do that ebay or cl don't or can't do. I've never used ebay, hardly used cl, so I don't have a source of pain to suggest. Since you came up with the idea, hopefully you have something that really pisses you off, perhaps the very thing that motivated you to do this in the first place. If it's just spam, they seem to be doing OK right now.