[gentoo-user] A Theoretical install Question

Ok,  Here goes...
 
 
How large is the package archive for gentoo, assuming a full copy of the
portage tree, and all of the source tarballs in the distfiles directory
of the average server?
 
Would it be possible to draw down the whole archive all in one shot
using wget or similar, dump it all into a directory on the hard drive,
and direct portage there for the distribution files?
 
I know this would basically be equivelent to making a local mirror of
the distrservers, and I would have to make sure that my portage tree
matches up to the files actually on the hard drive. ^^  What other
concerns would I need to look at at this point. :P