It was only made for about a year but its similar to the model 199. That price is cheap if it's not spitting lead. That was purpose built as a target revolver, albeit an affordable one by 1938 standards that was NOT 'cheap'. That's hand fitted pre-war gunsmithing you are talking about. A source at THR says they sold for $30 new and in 2007 could go $550-900.
pic of one here:
http://www.thehighroad.org/showthread.php?t=459265 in really great shape, and I'd say that is well worth the asking price.
basic info FROM CTD:
ULTRA SPORTSMAN MODEL 777 - .22 rimfire cal., 9 shot, large frame single action top break, 6 in. flat top oval shaped barrel (same as the Model 199) adj. front and rear sight, elevation screw on front of barrel just above muzzle, oversized one-piece checkered walnut grips (eleven different styles available), straight trigger, arched hammer spur, cylinder release is a vertical lever on the right side of barrel lug, rear of cylinder has the patented H&R safety rim, finger rest trigger guard, trigger pull factory set 2 ½ to 3 pounds, hammer mounted firing pin, serial numbered in its own series U01 to at least U900, markings on top of barrel rib: "HARRINGTON & RICHARDSON ARMS CO.", left side of barrel: "ULTRA, WORCHESTER, MASS. U.S.A. H & R No. 777", right side of barrel "22 Long Rifle CTGE. SPORTSMAN". Mfg. 1938-1939.