My advice is to start by searching for "free VST," then take some time to go through each site, as there are many sites out there that collect links to free VST instruments and effects. But be sure to follow the links to the developers' web sites so you can see what else they've made. There are also articles devoted to the "best free VST plugins" and so on-- best free virtual instruments, best free soft synths, etc.-- so you can search for and read those articles and follow their links. Those types of articles are often revised from year to year-- e.g., "best free VST plugins for 2014."
You'll probably want to look for a plugin or DAW that can play samples, so that you can broaden your search to include free samples, free soundfonts, etc. SynthFont is a good free DAW that can play samples and soundfonts, and there's a version of it that can be used as a plugin in your DAW of choice. I'm not saying it's the best, and there are others to choose from-- but I'm more familiar with SynthFont myself.
You mentioned Asian instruments. You might want to narrow your searches by adding specific instrument names-- e.g., "free koto VST," "free sitar soundfont," "free shinobue samples," etc.