What Ethernet shield to buy?

I want to buy a Ethernet shield. However, I read some cheap ones do not not use the default Ethernet library and would work different from the orginal Ethernet board because of a different chipset.
My budget is ?0 to maximum ?40.

this is within your budget: Tektonica

Thank you! But I don't trust Tektonica. I was intending to buy my Arduino from them, but I decided to buy them at e-lioness. Tektonica is nowhere else mentioned, and all the products and descriptions are the same like another site (I forget which).

DFRobot make one that is sold much cheaper than the official one, but it uses the official library because it has the same chipset (Wiznet 5100). Widely available on Ebay and many micro-controller vendors. The ones to avoid unless you're seriously strapped for cash are ones using the ENC28J60 chipset.

Typical example of the DFRobot board : http://cgi.ebay.co.uk/Arduino-Ethernet-Shield-(W5100-Chip)-_W0QQitemZ220592149599QQcmdZViewItem?rvr_id=&rvr_id=&cguid=d869b7ac11c0a0e204878047ffe56b99

all the products and descriptions are the same like another site...

That is not unusual, a number of resellers use boilerplate text on their websites.

I have no direct knowledge of Tektonica, I got their name from here: ttp://www.arduino.cc/en/Main/Buy

Thank you very much, Pluggy! That seems to be a good choice!

I have 2 of them from the same vendor, no complaints.

I'm going to buy one from Yerobot.com. ?22.00 (or £19.00 or $29.00).
http://www.yerobot.com/arduino-ethernet-shield.html

Looks like the same guy, I never connected with him off ebay.