Sigsauerguns.com has them, I just ordered two although they are higher then most at $54 each. They are just too hard to find right now and I know I want them soon. My wife hasn't fired the P238 yet and I know that extension will make a difference for her as well as the new grips I ordered. If she can't hang onto it properly she will have problems and I want to avoid that because she is really new to shooting.
Here are the grips I ordered.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=360345110077
Here are the grips I ordered.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=360345110077