Lone Star started making them again for a while. Then they had the fire. So I am not sure if they are back in production.
The Scat Cat is a very basic and classic design that dates back to the early 1980s, and was sorta the standard of performance when we raced with K&B .40 engines around then. The ScatCat design sorta found its limitations when engines moved beyond the Rossi and Webra .40 in the 1990s.
Word of caution for "original" scat cat builders - the front wing attach dowels are the weak link. Especially if you are sport flying and pull any sort of outside loop or negative G manuver. I converted all of mine to 4-bolts following the time in 1983 when I found that out
Also, my later scat cats did away with the wood spar/gear block - went with a small blade spar and a few layers of 2oz glass on the center section (as seen on similar designs).
The China Clipper and Sonic 500 were similar designs, but not 100% faithful in constuction. I also recall that the wing airfoils were slightly different, but not something most will notice.
If you like the low-wing Q-500 layouts, look around for plans for the Viper (the original Doug Whittaker design, not the ARF you see today) - scrach built, and you can usually find wingcores from the commercial foam wing companies. It was a step-beyond the scat cat in performance and construction, and had all of the same great flying qualities. Could be built conventional tail (my preference) or V-tail.
Matney Models PitBull kit is glass fuselage, foam wing - same basic layout, and quick - only about $100 for the kit .
Also worth noting, Matney has the wood/foam/glass DawgGoneIt available now too. Nice plane, very quick, V-tail. Foam wing and stab. Costs about $115 with shipping (photo) - not on the website yet (should be shortly), but you can order one by calling