Wifi usb
From ElphelWiki
List of USB WiFi adapters, what is acceptible from newegg.com, and probably can work with GPL drivers:
Name: ASUS WL-167G, Ralink RT73 based link: http://www.newegg.com/Product/Product.aspx?Item=N82E16833320107 ~$20 information about Linux: http://www.murrayc.com/blog/permalink/2007/02/17/linux-compatible-wireless-usb-adaptor-results/ - post in the comments, "Jon Smirl Says: ..."
devices from this list: http://linuxwireless.org/en/users/Devices/USB
TRENDnet TEW-429UB http://www.newegg.com/Product/Product.aspx?Item=N82E16833156161 $50
3com 3CRUSB10075 http://www.newegg.com/Product/Product.aspx?Item=N82E16833105022 $44
IOGEAR GWU523 http://www.newegg.com/Product/Product.aspx?Item=N82E16833139116 $27
level one WNC-0301USB http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=2052810031+50011109&name=LevelOne $25