Show Legitimacy When Doing Business On The Web
If you wish to be taken seriously when doing business on the web you must give some indicia of legitimacy. That applies to you whether you are buying or selling.
The web has developed to the point where any legitimate business has a registered internet company name (domain name) and a web site of some form - traditional site, ecommerce site or blog.
If you do not show them to people you are contacting, you indicate that you are NOT in business.
There are two aspects to legitimacy. One is the actually process of becoming legitimate. And the other is looking legitimate.
If you send email over some public service - as opposed to over your domain name - and do not include your web site address, you are likely to be ignored. Or if you are not ignored, you are likely to be treated with caution or as a time waster. See Look Profession Or Get Ignored
It is not expensive to have at least a product blog. In any case, every company should have one even if they have a web site. So you can start with that. It is a great image builder and establishes that you are serious. Read about Product Blogs
If you do not have a domain name, start by reading information about What Is A Domain.