An Arduino Uno costs $30. An Uno with Ethernet costs $65. A Raspberry Pi with Ethernet, 512MB RAM, HDMi video and an SD card slot costs $40. An Adafruit Ethernet shield sells for $45, more than the complete Raspberry Pi.
Presumably the adding Ethernet to a Pi cost a few dollars. Why is Ethernet so expensive with Arduino?
Julian
cause its custom external hardware no one uses to handle the bulk of the interface, the pi has it in the chip to start with
Looking at the schematics, the Raspberry Pi seems to use a LAN9512 "Hi-Speed USB 2.0 hub and high-performance 10/100 Ethernet controller". On Digikey these are $3.80 for 100+.
The Wiznet ethernet chip used in the Uno Ethernet costs $4.76 for 100+ from Sparkfun.
These two solutions seem comparable to me. I still don't understand why adding Ethernet to an Arduino costs more than the Arduino on its own. I appreciate costs go down with volumes but an Ethernet shield is still at the top end of shield prices.
In another thread someone proposed to use the Pi as the new ethernet "device" for Arduino.. Makes sort of sense ....
These two solutions seem comparable to me. I still don't understand why adding Ethernet to an Arduino costs more than the Arduino on its own. I appreciate costs go down with volumes but an Ethernet shield is still at the top end of shield prices.
The schematics and circuit board design are available, at no cost. The list of parts used is available, at no cost. If you think you can source all the parts, and assemble your own board cheaper, go right ahead.
eried: That is an ENC28j60 chipset, not a Wiznet. It will gobble up the ram on an Uno like nobodies business, and the standard ethernet library doesn't support it AT ALL.
BTW: If you think the ethernet is expensive, look at the WiFi.. EeeGads.. I suppose if you HAVE to prototype a WiFi setup... Remember the Arduino is just an educational/prototyping platform. Prototyping is generally always more expensive than mass production, even if this is prototyping on a mass scale.
UnaClocker:
eried: That is an ENC28j60 chipset, not a Wiznet. It will gobble up the ram on an Uno like nobodies business, and the standard ethernet library doesn't support it AT ALL.
BTW: If you think the ethernet is expensive, look at the WiFi.. EeeGads.. I suppose if you HAVE to prototype a WiFi setup... Remember the Arduino is just an educational/prototyping platform. Prototyping is generally always more expensive than mass production, even if this is prototyping on a mass scale.
Little extra <10 usd
get the last comment ethernet shield + this mini 5V portable wifi router 
Find out what a 56kbaud ethernet modem cost in 1984, and weighed, and you'll be congratulating the engineers for cutting those by quite a few orders of magnitude.