If these were massed produced where you could sell 10,000 of them then the price would be lower. It cost so much for the molds the equipment to make a coil, plus the labor to design one of these coils, the to build one to test only to find out it don't work like it should, so back to the drawing board and start over. What i am saying is to make that first coil it may cost $25,000 or more, so if you sold one the cost would be $25,000 for the coil with no profit. The materials didn't cost much and maybe less that $10, but everything else that went into it is what cost. If you sold 25,000 of these coils you would have $10 or less plus divide the original cost to make the first one and you will have around $11 in it. Now to make a profit and sell to the dist you have to sell for more than your cost, then the dist sells to the dealer and he has to make a little too, so now this coil is at lets say $30 now. This sounds like a reasonable price if we sold 25,000 of them and everyone could live on less then $5 profit, but in most case less then 1000 are sold of the after market coil and people have to make Little more than $5 on each coil to survive as a dealer, so now that cost per coil is a lot more.
Now these were just make believe figures to show you what is involved as I am sure it cost a lot more for the research and development of these coils and if these could be massed produced the cost per coil could be less.
I used to repair TVs and when tubes were used in TV before sold state a lot were made, so the cost was less then $1 sometimes depending on the tube as it was massed produced. Now as time went on and tube were used less and less there were less being made and the price went higher until there were very few used. Now they were only made for one day a year, but these same tube went from less than $1 to over $35 as they were no longer massed produced. If all coil were made the same with the same freq and the same connectors so only one 5 inch coil, one 6 inch coil and one 7 inch, one 8 inch and so on was made these would cost less to make and cost the customer just a fraction of what we are paying.
Time for me to get off my soap box, but just wanted to let you know why we have to pay the price we do if we want different coils.
Rick