Building them here isn't that difficult at all. They're relatively simple, as far as electronic goods go.
Getting insurance is nearly impossible though, as US manufacturers have a significant disadvantage over foreign manufacturers and importers when it comes to liability.
In other countries, if someone does something stupid with your product and hurts themselves or someone else, it's their fault. In the US, if someone does something stupid with your product and hurts themselves or someone else, it's their fault if it was imported, but if the manufacturer has business operations in the US, than it's the manufacturers fault. You might get the importer to stop carrying that exact SKU, but you're not getting any money from them, and they'll just import it under a different SKU.