I've heard that you might be able to airbrush Tamiya paint out of the bottle. Even though I've also read posts that people thin their Tamiya paint too, ~25% thinner or so. BUT that's just what I read in forums, my airbrush is still in the mail somewhere. Lots of websites sell Tamiya paint, and brick and mortar hobby/craft stores too.
edit: The Fine Scale Modeler forum has a lot of info on airbrushing. Check it out. http://www.finescale.com/fsm/community/for...asp?FORUM_ID=18
some Tamiya online store links
www.hobbywarehouse.us
www.best1hobby.com
www.hobbyfan.com
www.hobbylinc.com