Japanese startup Coccolo is going to sell a monocular HMD (head mounted display) for 29,800 yen (~$250) in Japan this December.

According to Nikkei.Net (Subscription) the Coccolo costs only 1/7th of the currently available HMDs in Japan.
The Coccolo HMD has QVGA resolution is is fairly tiny. Battery holds for 6 hours of viewing video.
The Coccolo site (Japanese) does not have a product page of this particular HMD up yet.

Not sure what stores in Japan will carry the Coccolo HMD, but $250 is a low enough price, that I would give this HMD a try to see how it performs.

See also our review of the Accupix MP Glass MPG-230A HMD Video Glasses.