Pros and cons of different OpenBCI sellers, and is it worth to buy OpenBCI modules & which are the alternatives?

There are many offers on www.openBCI.com, ebay and Aliexpress for OpenBCI modules. Some offer only a short money back warranty, some offer support and warranty. The community is small for EEG devices. The costumers have to pay for the costs for support and warranty, if there is one. If we look at these arguments, it …