I have not tried Tamiya's primer, but I know a bunch of guys who swear it's the best primer on the planet. I use Duplicolor's Paint Shop Primer http://www.google.com/products/catalog?q=duplicolor+primer&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&tbm=shop&cid=14111129068840701275&sa=X&ei=BQRdTsj4NsqjtgeIxbjRAw&ved=0CEYQ8wIwBg
It comes in quarts and is very economical. It lays down smoothly when properly thinned.