well I can't find any info on the web about 4wd Tamiya Mini chassis.
And since the HPI's are discontinued, they'll pop up every so often.
But if you still want one, the Xpress ones can be bought directly from the manufacturer. They still have some.
www.rc-xpress.com
They told me the regular kit was $80
and the Pro version with all the red aluminum $170.
I think these prices include shipping so it's a real bargin.
The company still has some legs apparently in HK so it's not discontinued.
Email them if you are interested. They only accept bank draft for international orders whatever that means. I'm having a friend pick one up for me in HK.