How about carrying the WIZnet ethernet modules? the WIZ810MJ has a single-quantity price of $12 shipped from the manufacturer. I’d buy them from SFE for $20!
Why pay more to get the same thing ?
$30 & up shipping fees from Korea.
true, but its a new product and will be stocked in USA soon.
im sure www.saelig.com/ will stock it.
Saelig are stocking it (the W5100 chip, rather than the whole module) right now, and it’s easy enough to make your own breakout board for them. I just bought ten 
Seven bucks a piece. (I just wish shipping across the pond wasn’t quite as expensive for what must be a tiny package).
http://www.saelig.com/miva/merchant.mvc … gory_Code=
I wish I’d seen this thread before buying a couple of CP2201s. I suppose I can always ebay 'em (but having said that, they aren’t that expensive so I may keep them for a project).
I just purchased two. Integrating one with a mega128 (ETT) for an application I have in mind.
$17 ea + local US shipping.
Wiznet have just started selling the W5300 too, which is like the 5100, but has twice the available IP stack software sockets (8 for the W5300, as opposed to 4 for the W5100) and more buffer memory. It’ll also manage a throughput of 50Mbit/sec. The W5100 is capable of 25Mbit/sec throughput.
If you are going to make your own breakout board for the W5100, this is what I learned from making mine…
It’s a 0.4mm pin pitch package, so make sure you pick the right package type in your PCB layout software! (Most LQFP footprints in my PCB software are 0.5mm pitch)
You need a good ground plane. While my home made W5100 breakout board works fine, I have suffered problems which I strongly suspect are caused by ground bounce (problems encountered the more data bus lines are set to logic high). I found I could mitigate these by adding a 74HCT245 bidirectional buffer or pull-up resistors, though. (Mine’s on a microprocessor bus with lots of other devices). My home made breakout board is only two layer, and since I must use fairly large vias, and can’t put vias under the chip, the ground connections aren’t quite as good as they could be and the decoupling caps are perhaps a few millimetres further from the chip than if I had a factory made PCB.
I used the Tyco Mag45 magjack, but the rest of my breakout board is built as the reference schematic from Wiznet.