I find it expensive because it is $6 per (1 unit break price, I know that there is a discount at 1k and a discount via buying through a CM commencerate to the CM's yearly spending with each distributor)
Which means that on the board with 4 of them there is $24 in just connectors (+/- discounts) and wile each of them has 240 pin and only 48 of them are actually used meaning 912 pins are unused.
By elimination the connectors and switchon to a 52pin pci express board edge connection it would allow the same ammount of GPIO pins, remove the connector cost from the board almost entirely (minor additional costs for the board manufacturing) also, since the board needs to be vertical for fanless operation a backplane for connection mulitple boards would be completely ideal in a configuration like this and the connectors for the backplane are sub $1.
After looking at connectors for a bit I have only found one downfall to a doing a pci express board edge connection in to a socket such as this:
http://www.digikey.com/product-detail/e ... ND/1002341and that downfall is that it would limit the connection to 5gb/s in each direction. (requires gen2 pci express for 5gb/s)
the samtech connectors are fantastic connectors on paper for sure. but I personally just feel that in practiacl application that are overkill for the task and dificult to source in hobbyist/research quantities due to a low level of addoption in COTS products.