There are many forums and places where Amazon sellers congregate online, if you can find where these audiences congregate then this could be a way to approach them.

If you have found niches is there any reason you wouldn't want to develop an online presence yourself?

Platforms such as Amazon, eBay, Etsy and Shopify make it very easy to get going.

There are even software tools to allow you to manage platforms centrally.

The cost, knowledge required and the barrier to entry is low, and once you can see what is working via the platforms, then selling directly via Shopify or similar can help you get even higher margins

Good luck!

We live in a technology world where everything is in our hands. Grab your phone and tells your opinion on your twitter, instagram and etc.
That way you can negotiate with them and there must be someone who is interesting with your ideas.

First step in selling product ideas is to find them out. Before you begin searching the depths of the internet for business ideas and the ends of the earth for products and niche ideas, it is always best to start with the ideas you already have. Maybe it is a product or idea you have had for years. The product born of passion attracted the attention of influencers that made the brand a nationwide hit, online and in stores. Dog owners would become frustrated with unreliable products, and the expenses can quickly add up. The market for that product was based on this one specific pain point.
Paying attention to trends in brick-and-mortar retail and adapting them to ecommerce can be just the ticket you need to create a profitable and unique internet business idea. This also supports the small business movement, allowing customers to buy from select local grocers.
You can read more here: https://www.shopify.in/blog/product-ideas
Now, the selling part. Living in a concrete jungle allows for some creative concepts. Step out on the streets – In an online age, there is something to be said for going au naturel and exercising a little IRL marketing. Urban living results in some unique marketing opportunities you will not find elsewhere. Photo contests are great for a number for reasons – they are relatively easy to enter, and they also provide sponsors with a great form of user-generated content that can be reused and implemented elsewhere. Submit your vote contests - Voting contests get a ton of entries because they are so easy to participate in.
You can read more here: https://www.wordstream.com/blog/ws/2014/06/12/marketing-ideas

Besides if you do have any questions give me a call: https://clarity.fm/joy-brotonath

Absolutely! There are many online forums and mediums that are available that will allow you to sell product ideas online. I would focus in on free mediums first such as Reddit (forum), specific Facebook groups, and other like-minded websites that will allow you to sell some details of your niche.

Another way to do this is to reach out directly to Amazon sellers in similar niches or types of products and send them an email that you have an idea for X product in X industry and can provide them specific information that they will be able to profit from.

Warning: Ensure that you have "sold" the idea before providing all the details to the buyer. This way you can ensure that you are not giving away the idea and everything that comes with it, essentially for free. Ensure that you provide enough details to sell the idea (category, industry, what country, etc.) but be careful of the amount of details you provide.