Supply, demand, and hype. That's the gist of it. Hanko's generated a strong cult-like following on Facebook which has fed the demand, and generally has always had a stronger presence being US-based. Jeff Hanko shows up to a lot of the main events (ie. the Gathering) to sell his products too which adds on to the above. Tain is a bit more off the radar being in Taiwan, and has never exhibited much of a presence online through any platform. They're probably close to par in terms of quality, but marketing presence makes all the difference.