Right now on eBay, there are several different brands of blades that are listed as Israeli Personnas. They are Q-Ball, Crystal, Royal, Viking's Sword, Tomy, and Personna (red). Is there any difference between these blades, or should I just buy the one that is cheapest? I am currently using a Crystal blade that another member PIF'd to me and I'm really liking it. I'm getting great shaves with it. I'm getting ready to make a bulk purchase of them, but couldn't help but wonder if these blades are all the same.