I don't fool with them after selling just a few to friends and hearing back from them after the things broke. Besides, being an avid wine drinker myself, I use quality, efortless corkscrews and the days of trying to pry a cork out of a bottle by tugging on a corkscrew are long gone.
To me, selling cheap things for the sake of making a few dollars is not worth having friends and repeat customers think all of my work as shoddy and cheaply made.
For the exact same reason, I stopped using the various plated brass stopper bases and have switched to stainless steel and silicone stopper bases.