alright, from http://www.newegg.com
I found the best deals for you:
GF4 TI4600 VIVO for $228us
GF4 TI4400 for $190us
both have free shipping. And basically it's a matter of do you want to pay an extra 38 bucks for 25mhz more on the core and memory by default, and for VIVO. Now I should tell you, the TI4400 can easily overclock to TI4600 speeds. But for 38 bucks more, ya I'd get the TI4600. And it overclocks even higher than TI4400 can.
So in conclusion, it's a matter of how you wanna spend your money. But I will say that $228 is a VERY good price for a TI4600 with VIVO. I paid $248 for my TI4400 VIVO only a couple months ago.