in my experience it is better not to create the wheel from allover again unless it is very big wheel. So if the business size is small or even medium then i would recommend to subscribe in any marketplace that is already there till the business's size justifies the expenses that will incur to have a market place. having market place does not stop at the point where it offers the local product or company products only, it has to evolve and offer others as well to the extent where it will be its own market place for others as well. The rule is simple, if it does not grow it will die or stay small at best. Hope this helps and open for a call if more is required.

Here the big question rather is to either integrate yourself with the key online marketplaces, or to build your own. You need to build a integrate vs build assessment focuses on potential ROI, so you can see which way is more profitable and more aligned with your strategic goals in the long-term