I don't know exact numbers of how big the market is but its big...

I don't know exact numbers of how big the market is but its big enough for people to try to copy it.;-) This new machine retails for over $10,000. My understanding is the copies of the previous model were useless junk compared to the real model. They are highly sensitive instruments, even a thunderstorm 100's of kilometers a way can cause interference. Minelab detectors come with verification codes now to check before you purchase. I also know that the coils are chipped to only run on the correct model.

Since the early to mid nineties Minelab(Bruce Candy), have been the benchmark in gold detectors as they have been the leaders in getting the most depth from gold detectors. They have been able to get more depth and sensitivity with each new model which makes it worth while for prospectors to go over the old gold fields again as gold nuggets laying deeper than previous models could see, can now be detected. Its been six years since their last flagship model release so most gold fields are considered cleaned out by guys with the previous model. Hence the excitement with the new model being released. The model they released last year is considered their mid range detector which has proven the best machine for finding tiny nuggets. It seems they have the 'top end' market well covered at this time. You see some grumbling on the forums from people about the cost of their machines as everyone would like a cheaper machine but you either cough and buy or you have to try and find new ground that hasn't been prospected by one of these machines. This also keeps the re sale on used Minelab detectors high, used models are typically only be a few hundred dollars cheaper than a new one.

Just FYI I have no affiliation with Minelab. I have friends who have prospected for gold since the mid nineties and done very well for themselves even when gold was $300 an oz. They don't hesitate at ordering every new release by Minelab. I have found some gold myself with their previous flagship model(GPX 5000) and I can tell you they are quite an incredible machine to say the least. Definitely 'top of the range' and definitely an Aussie success story.