Why Do 12" Tonearms Cost So Much More Than 9"?

Right

Woops, Brain fart!

Hi guys. I bring greetings from French Guyana.

I'll side with Lewm on this one. Because the people who will go for a 12" arm will pay those prices. It is all about what the market will bare. I'm going to start a new thread on cartridges shortly which brings this into focus.

Is a 12 inch arm better? Overall with medium to low compliance cartridges, a little but it depends on the arm. In many cases not at all and in some, worse. The real jump is to arms that can stay tangent to the groove and are straight avoiding the skating problem altogether. There are several arms available that utilize Thales geometry and normally pivoted but straight arms my personal favorite being the Schroder LT.
The Reed 5T is another example. These arms stay tangent to the record, do not skate and totally avoid the problem of very high horizontal mass which plagues the vast majority of designs.  

Since SME was mentioned, when new the price difference 
between the more commonly sold 3009 and 3012
was not a multiple of its additional length.
 
As years passed the greed factor followed exponentially so
lets be honest.

It has been said that a tiny error in setting up a 12 inch arm has greater consequences for tonearm alignment error, than the same error made in setting up a 9 inch arm. I actually have never bothered to investigate the truth of this axiom, but it is worth noting. 

Being horrified by prices of 12" arms, and deciding, if I'm going long, I'm going LONG, JVC long arm 7082, terrific if rubber fixed, is actually only 11-1/8" Many 11-5/8" ...

After searching, I found a 12.5" arm, love the simple physics, looks, price. No returns, from Russia, no "yeah, good choice" from anyone, put myself thru the wringer for months, finally decided to risk it (along with Square Trade Warranty).

Not for the feint of heart, these guys don't believe in Din connectors, so you need to solder the tiny wires to the junction box they supply. The smallest delicate wires I have ever seen, Litz, silk coating, I thought a few strands, actually 37 strands, I still cannot believe it. I put it off, was going to find and pay someone, then "only thing we have to fear is fear itself", so I got my 30 power shop light and did it.

I learned here how much more important alignment is for long arms, so I upped my tools and inspected my work repeatedly like someone else did it.

I'm very glad I did it, only cost $850. plus tax and shipping, now they sell it for $950.

https://www.ebay.com/itm/tonearm-tonarm-12-long-NewArtVinyl-BLACK-BIRD12-5-CARBON/233512433389?hash=item365e6cf6ed:g:CUMAAOSw86ZeXTqK

text was english, now Russian,

web site, english translation via Google

http://newartvinyl.ru/

One thing about a long arm, for me, is that there is enough space between the arm base and the TT edge to locate this very nice auto-lift

https://www.amazon.com/gp/your-account/order-history/ref=ppx_yo_dt_b_search_od?ie=UTF8&ij=&opt=ab&ref_=&search=112-9890941-6780204

no room for one for my 9" arm.