Hobbylink Japan and other online sellers are your best bet. If you plan to repaint them, then it's easy and you don't have to worry too much about the random selection. They are not gaming models. They are collectible models based off of an incredible range of garage kits.
In the past, I have picked up cases from HLJ aand on Ebay. This is the most economical way to pick them up if you are planning on getting any large number of them.
-Eli