Wifi conectivity for arduino

Hi!
i was thinking in buy something to give connection to my arduino. At the beginingn i think i something wired [0], but in my last work, i used a module wifi called Connect One iWifi [1]. The last ones is too much expensive than [0] and [3]. I find another wifi module that is cheaper than the other and i can get here in Chile.
So my question… what is better to do? anybody has experience with [4] and the arduino?

Thanks!
Roberto

[0] http://arduino.cc/forum/index.php/topic,53388.msg381444.html#msg381444
[1] http://www.connectone.com/products.asp?did=73&pid=73
[3] http://cgi.ebay.com/Arduino-Ethernet-Shield-Based-Wiznet-W5100-Ethernet-/120692589433?pt=LH_DefaultDomain_0&hash=item1c19d6c379
[4] http://www.wiznet.co.kr/Sub_Modules/en/product/Product_Detail.asp?cate1=5&cate2=43&cate3=0&pid=1020