As far as I can tell there were 53 flying Hiperbipes in the world as of January 2010. Unfortuntly we lost one about a month ago in a fire...
As stated above the HB was never offered as a real "plans-built" airplane...you recieved the 4 wings, all wood and built like an R/C airplane wing; wood spars, wood ribs and plywood sheeting on the bottom surface all ready for inspection and "closing up" by the builder. The fuselage was delivered with the left and right sides welded together to form the airfoil shape but you had to fabricate and weld all the rest of the tubing...and there is a LOT of tubing! Add to that the nessessary fabrication of the alieron/flap mixer (a whole lota parts) as well as the whole rest of the airplane and you had a job in front of you that might span 3000 man-hours or more.
In 1977 an airplane called the Christen Eagle came out with a kit that included a pre-welded fuselage and tail group, built wings (ready for cover), pre-fabbed everything and a build time advertised at 1200 hours total.
For the Hiperbipe; the timing was simply lousy.
I own 7HT; a Hiperbipe built in the 1970-80's and with a lot of "Factory Love" lavished on it. It is a comfy cross-country criuser (160mph is my flightplan) and will pull +6/-4 acro all day long! Vne is 225 mph. The cabin is 47" wide, the whole front and top is plexiglas and the negetive stagger of the wings make it a not-too-bad biplane visiblity-wise. The best feature (in my humble opinion) is the fuel tank set-up...instead of the normal header tank setup where you burn your 2-3 gallons and then have to roll back over to replensh the tank the HB has a main tank of 29 gallons and a acro tank with 13 gallons...I can roll on my back, trim for level flight and criuse for over an hour upside down on the acro tank...
I'm the mod on the Hiperbipe site on Yahoo. Knock on the door and I'll let ya' in.