Hey Ed,
The prices are about right. but the engine was the Hanno Special MK II. The price for the MK II was significantly higher than the MK I while no significant performance advantage was enjoyed by the II over the I. When sales of the MKII dropped (stopped...) the price went down as well. I bought a MKII from Singapore Hobbies a few years ago and paid a whopping $212. The YS .61AR price was already heading down when the new version of the Hanno was released because YS (Mr. Yamada) accurately foresaw the impending demise of the 2-stroke 60 as the pattern powerplant of choice and by that time had released the 1.20AC which was the king of pattern 4-strokes for several years (until the brief lived 1.20SC and the 1.40L arrived).

Hey Chuck,
put your tach away. The YS .61AR is a strong engine [X(]! I've seen too many pattern 60s damaged by pilots wanting an extra 200rpm on the ground. Once airborne, the engine is a bit lean or the pipe a bit too short so the engine runs hotter than optimal. Pattern is about reliability; so run the pipe a little longer and the mixture a little richer and the engine will last for 1,000+ flights . Plus, you are now running an 'antique' - there are no more being made and no more parts available (commercially).
As for the AR, I found the APC 12x11 to work best. The engine likes to 'turn up' a bit more than the Hanno (I think the throat diameter of the carb is a bit larger on the AR). I've run nothing but K&B 1L gloplugs in my pattern engines for more than 30 years. If you're not getting 40-60 flights on a plug with no distortion of the element then the engine is probably too lean or the pipe too short.
Enjoy your AR!!
Will Bartlett