Sorrell Negative Stagger, Model 7 (SNS 7) was first introduced in 1973 and combined serious Biplane Acrobatic performance combined with a unique side by side cabin seating unlike other Acrobatic Biplanes like the Pitts, Star Duster, Ultimate Bipe & the Christen Eagle.

Controlling interest in the Hyperbipe is now with Tunderbird Aviation LLC

 

Every now an then they come up for sale on barn stormers and other online aircraft brokers.

Sun N Fun / Lakeland has one on display:

 

For RC scratch builders, Outerzone has some free PDF plans

1978, 42″ Span, by Frank Massa / Master Kit

Also from 1978, 57″ Span, by Phil Moore / Radio Modeller