I used to see a few on the street in boston about 10 years ago, now the only one I know of sits in a riding gear shop/cafe as a decoration...
A search turned up these two that make the one you linked to seem like a bargain.
By the way many parts for these are total unobtainium, so don't get any ideas unless it's a cheap wreck with good parts that's been sitting in an apartment since 1990.....
the legendary GB500 - $9500 (310)
Visit the posting at
http://losangeles.craigslist.org/wst/mcy/1718128847.html to contact the person who posted this.
the legendary GB500
Date: 2010-04-30, 11:46AM
Less than 800 miles, all original 1989, unmolested, tool kit manual etc. complete as bought by me, new...!(absolutely Immaculate, sits in the living room)
Location: 310
HONDA GB500 1690 ORIG. MI. - $7950 (SARASOTA)
Visit the posting at
http://sarasota.craigslist.org/mcy/1703696447.html to contact the person who posted this.
HONDA GB500 1690 ORIG. MI.
Date: 2010-04-21, 6:45PM
1989 GB500 IN "COLLECTOR CONDITION" THIS IS THE HONDA VERSION OF THE BRITISH 500CC SINGLES THAT RACED ON THE ISLE OF MAN IN THE '50'S AND 60'S. FINISHED IN "BLACK JADE" THIS IS A LIVING ROOM QUALITY EXAMPLE AND THERE ARE NOT MANY AVAILABLE.
Location: SARASOTA