Long ago, there was a time when the list price for Dura-Ace 7900 brake shoes + fixing bolts (one set for left and right) was
668 yen,
and at that same time the list price for Altegra 6700 brake shoes and pad holders (one set for left and right) was
set at 699 yen.
The shoes attached to the 6700 pad holder are the same ones sold individually for 668 yen,
so the pad holder itself was effectively priced at 31 yen.
I thought there would be plenty of people wanting to buy them separately for carbon rims as opposed to aluminum rims
(in fact, I'd suggest this approach myself),
so I stocked about 50 pairs, but they sold out instantly.
Of course this was a pricing error,
and the price was quickly raised (→1952 yen),
but something similar is happening again right now.

↑On the left is the 9000 R55C4 aluminum rim brake shoes + fixing bolts (one set for left and right),
and on the right is just the same thing but in 2 pairs.
Both are current products and readily available,
but the single set (left and right) has a list price of 818 yen,
while the two-pair set has a list price of 1160 yen.
Shouldn't it be 1610 yen instead of 1160 yen?
is what I suspect, but as it stands now, buying the single-pair version is
a terrible deal, so I'm letting you know here.
You might think that mentioning this would hurt our shop too,
but our stock of shoes is limited in quantity anyway,
so the one who'll really suffer is... (and so on)
In the 2014 catalog, only single-pair shoes were listed,
and the price before Shimano's
price increase on May 1st, 2015 was 757 yen,
so the current 818 yen for a single pair is the manufacturer's intended price, and
the per-pair unit price of 580 yen when buying the two-pair set is
clearly a pricing error.
This is likely to be corrected with a price increase soon, so
if you use Shimano aluminum rim brake shoes, I'd
recommend stocking up.
668 yen,
and at that same time the list price for Altegra 6700 brake shoes and pad holders (one set for left and right) was
set at 699 yen.
The shoes attached to the 6700 pad holder are the same ones sold individually for 668 yen,
so the pad holder itself was effectively priced at 31 yen.
I thought there would be plenty of people wanting to buy them separately for carbon rims as opposed to aluminum rims
(in fact, I'd suggest this approach myself),
so I stocked about 50 pairs, but they sold out instantly.
Of course this was a pricing error,
and the price was quickly raised (→1952 yen),
but something similar is happening again right now.

↑On the left is the 9000 R55C4 aluminum rim brake shoes + fixing bolts (one set for left and right),
and on the right is just the same thing but in 2 pairs.
Both are current products and readily available,
but the single set (left and right) has a list price of 818 yen,
while the two-pair set has a list price of 1160 yen.
Shouldn't it be 1610 yen instead of 1160 yen?
is what I suspect, but as it stands now, buying the single-pair version is
a terrible deal, so I'm letting you know here.
You might think that mentioning this would hurt our shop too,
but our stock of shoes is limited in quantity anyway,
so the one who'll really suffer is... (and so on)
In the 2014 catalog, only single-pair shoes were listed,
and the price before Shimano's
price increase on May 1st, 2015 was 757 yen,
so the current 818 yen for a single pair is the manufacturer's intended price, and
the per-pair unit price of 580 yen when buying the two-pair set is
clearly a pricing error.
This is likely to be corrected with a price increase soon, so
if you use Shimano aluminum rim brake shoes, I'd
recommend stocking up.