This HP Carbine stock from ATI makes them look just like the significantly more expensive Beretta CX4:
http://www.milsurpstuff.com/proddetail.asp?prod=HIP9000
For roughly ~$49-69, it makes a pretty decent improvement in looks IMO, and still keeps the cost from getting too ridiculous.
I should have never posted that link. Now I'm thinking about getting a HP Carbine just so I can put that ATI stock on it. lol