Here is my view as I see it. This is my opinion and hope not to upset yours. My apologies in advance if I do.
Vertical Jigging is nothing new it it just old styles of jigging that evolved into a specific style of fishing. I remember the good old days (it is still done today) when we used big spoons, diamond jigs, bullet style buck tail jigs and jigged for groupers, (on the West Coast they had their own versions of irons that are still used today), we used them horizontally, vertically, left on the bottom yoyo-ing it, or left them a drift, we then added a piece of bait strip, and then came the plastics that revolutionized some styles of fishing. The Japanese on the other side of the world came into play with speed jigging, they shorten the rods, and used metal jigs that resembled knives hence why many still call them knife jigs. It is said it was all because the Japanese commercial fishermen needed different ways to entice fish and this form worked very well for them and then caught the attention of the recreational fishermen. The Japanese worked very hard on the evolution of this style of fishing, many companies put a lot of effort in research and development for it which is the reason for the high price on their vertical jigs. My guess is that they did not put a patent in many of the jig styles because they knew that jigs needed to continue to evolve, changing form, color and size. Since fish seem to have a tendency of getting used to recognizing a certain pattern with artificial lures we have a tendency of classifying something that works or stopped working for us. We then look for something different, this is where you see (usually Chinese manufactured) copies of authentic lures start showing up all over the internet and it is when the Japanese companies start releasing the new, improved, and updated jigs. It is up to us to identify what our budget is and what can work for us and what just won’t. So keep the following in mind.
Usually knock off lures (imitations of the originals) lack what the authentic lures have, the action. Many authentic lures are designed to create a specific action, be it flutter, horizontal movement, side to side movement, always something that identifies the jig as an injured bait fish. This is something that is very lacking in most knock off lure. You can test them from a boat on a clear water color day and will see for yourselves. Buy an authentic lure and one that is a knock off, drop them until you can see them (you want to have some type of current so you can see what it will do in that condition) slow jig the vertical jig up and down and also try it fast up and down, then move your rod side to side. Not only will you have a comparison but will be able to see what type of action you want your jig to have. With knock off vertical jigs more than likely you will be the one doing all the work and not the jig it self. You will have to jig it left to right pulling upwards side to side so it can have the desired action. So why is that? Isn’t an exact copy? Well, sometime it is some and sometimes it isn’t. Quality authentic lures are made up of different alloys while a knock off is usually made with just lead. The way the lures were made also has a big difference, quality vertical jigs may have air pockets strategically placed so the jigs will have the action they desire them to have. The paint finish and quality of the foil also has a lot to do with it. Many quality jigs can last months if not years of use while jigging and the paint or foil still looks great while a knockoff may loose it’s color and brilliance on the first day of use. Sometimes saving money isn’t saving money but when it comes to loosing jigs to toothy critters, then knock off may be a solution if you want to catch them. I my self prefer to make some home made butter knife jigs when that happens. I had bought many knock offs before, but lately I am leaning towards using better quality jigs. Remember the company or people that make knock offs of a non patented vertical jig are not braking any laws. So it is legal for them to sell the product and it is legal for you to buy it. But please realize is the cheaper product that you are buying what you really need? Or is it the quality original product that was tested and proven to work that you really should use? It is your decision, hope you make a wise one.