Getting the software is a breeze if you've ever looked on the usenet
The ROMS are easily found using bittorrent or on IRC...
all this can be found via google
modding it takes an experienced modder less than 15 minutes....
you can pay a modder in your town to throw the chip in for under $20.....
putting the harddrive in is a piece of cake...
I don't think you'll be looking at much profit
most people when hearing a >$400 price tag for a $200 xbox will just go and learn how to do it themselves