I think what you've got might be called a votive tablet, votive plaque, votive amulet, or votive stele (sometimes spelled stela; plural=stelae). Besides Buddha, another word you might search for is Bodhisattva.

I'd recommend searching with Google Images. I've been doing that for a while now. Here are the most interesting objects I've found so far, but they're still not very close to what you've got:

http://www.ancientresource.com/lots/asian-artifacts/liao-dynasty-buddhas.html

http://www.thebuddhasface.co.uk/thai-buddhist-votive-tablets-122-c.asp

I'd do more, but the computer I'm using right now isn't very conducive to fast downloading of images.

Here's a sample search results page.