Those things are really cool, especially when they hit that low not and let it drone. I've seen 'em in asia for anywhere from 2000RMB (about $300) to 10,000RMB (about $7500) and probably more. I don't think it would be too difficult to build one, especially if you have some woodworking skills, but it might help to find a cheap one or borrow one so you can have something to work with, just to have a tuning guide and give you an idea on bridge placement/usage. I thought about making one myself and when I get back to Canada and my tools, I just might try. I'm definitely interested.