1) By buying from a non-authorized distributor, you are revoking support from the authorized distributor in your country (I'm assuming US or CA). If the seller provides support, you're in luck. If not, you may have to return your cartridge to an international service center which will cost you both time and money. This is Gray-Market selling and although discounted, you may ultimately pay the full price, one way or another. Depends on your willingness to gamble. I've only done it once but had absolutely no problem.
2) As mentioned in the other post, I would not be happy to find a cartridge with a bent or misaligned cantilever. BUT, I had that very thing happen with a local audio salon, and they quickly resolved it for me. Cartridges are small and fragile and I seriously doubt that quality control goes so far as to inspect each cartridge. Perhaps a discerning seller SHOULD do a visual check before shipping.
The five-day waiting time without response is certainly long, especially when it's your money that's involved, but in reality, five days is not a long time to get response from a seller, especially in an international sale. Responses to me from Oracle and Sonic Frontiers have taken longer, but they have never failed to respond. Nonetheless, I would like to keep appraised as to how the situation gets resolved.
3) There is one seller, 2Juki, on eBay that has done a tremendous amount of business in high-end analog products. That seller currently has over 200 transactions, and over 200 positive feedbacks, and only one neg. This seller also has offerings on Audiogon. If this individual was a less than honest, this level of positive feedback would not have occurred. Most of these sales were for the upper end of the analog range and were not sales made to undiscerning buyers.
Best of luck in your quest.