cool!!! I started sculpting and customizing in 6" about a year ago, but only did 2 thus far. I've since went back to 3 3/4" scale. But MAN, those are danged awesome! You may want to look into WWE wrestling figures too as bases. Thats mainly where I did mine from. You can get lots of good fodder cheap from older figures. Weapons, now thats another issue. Not much out there. I used those cheapo paintbrushes as a lightsaber (the kind that come like 10 to a pack with different colors for handles) and it works very good.
Have a look (its the Naga sadow and Gorc). of course, I'm not really sure if gorc is 3 3/4" scale or 6"! http://rjedi-pics.tripod.com/cus-naga.htmlhttp://rjedi-pics.tripod.com/cus-gorc.html
I also found a TON of less articulated 6" army soldiers at big lots as well, for 2 bucks each. Hope this helps a little.