Comment Affordable ($80) Ergonomic Mechanical (Score 1) 310
Unfortunately the subject is a little misleading, because of how hard it is to get the particular keyboard I'm talking about. I'm lucky enough to have family and friends in Korea, and there was a company (which looks like it went out of business) called ARON Tech or ARON Digital that made mechanical keyboards. One of their models was an ergonomic (split middle) one, which I managed to snag. I love it. When I purchased mine, it ran for about $60 after the exchange rate. The USB version (which is what I should have gotten) ran for about $80, IIRC. Unfortunately it is supposedly tough to find these keyboards in Korea now.
You can see a photo of the keyboard here: http://fv521.egloos.com/2791639
Web archive also has a good set: http://web.archive.org/web/20030202083656/http://arontech.com/
The reason I mention this is because it looks like ARON just farmed out their manufacturing to a Chinese firm, and it appears that you can still get these keyboards:
http://www.diytrade.com/china/2/products/3290484/%E8%AF%9A%E6%8B%9B%E6%B8%B8%E6%88%8F%E9%94%AE%E7%9B%98_%E6%9C%BA%E6%A2%B0%E9%94%AE%E7%9B%98_%E8%A5%BF%E5%8D%97%E5%8C%BA%E5%9F%9F%E4%BB%A3%E7%90%86%E5%8A%A0%E7%9B%9F.html
OR
http://www.fzsky.com/aron/us/Pro_Show.asp?ArticleID=91
I'm also interested in a mechanical ergonomic, specifically for the USB interface. My current mechanical ergo is PS/2, and while it works great, and will for the foreseeable future, I'd also like to have a USB one.