Before purchasing any WiFi shield I'd suggest taking a very close look at the technical specs and particularly at what library they ship with.
The CuHead may be less expensive than some, but it is based on the Asynclabs WiShield. Asynclabs has gone out of business I am not sure there is much development on the library going on.
If you already are using an Ethernet shield I would actually suggest you get a little pocket router like the TP-link tl wn703n. I think I paid less than $30 for mine. The device is smaller in footprint than an Arduino UNO and uses USB power so you should be able to power it directly from the Arduino's 5v.
The beauty is that you can still use the full functionality of the Arduino Ethernet Library!
At the same time you have the easy configurability of a router through a web interface. Actually, perhaps you use another Tp-link router 702 or 3020 because the all Chinese web interface on the
703 takes a little getting used to with the help of google translate