the fry's just south of portland oregon had g dongles for $10 and n dongles for $15 last week. they were not a brand I had ever heard of. but you might want to try them if you are headed by a fry's store.

If you wanna buy one just get this Rosewill one

http://www.newegg.com/Product/Product.aspx?Item=N82E16833166037

at least it has a brand name so you might have a (slight) chance of finding someone on the end of the line when you encounter problems.