Are the Madra tips still available?
No, Ace Demers passed away some years ago, his son Jim attempted to run the business for a while, then they closed it down.
FWIW the lure of the Madras tips is not in measured performance, they really do not make any measurable difference in the numbers, but the feel, the stability, at low speed is greatly enhanced. I've flow a 150 with the Madras tips, and it was much more stable at low speed.
A story I've told before. When I was a mechanic in a small shop in Columbus, GA, we had a customer who had two identical 182's he used for parachute jumping. One day he walked in with a large box and put it down, and told us to install those Madras tips on the jump plane that was on the ramp outside, which we did. A couple of months later, he walked in with another box with another set of the Madras tips. The guy was a retired Army Sargent, a former jump instructor with thousands of jumps, he was a kinda hyper person anyhow, but that day he was especially wound tight. Turns out the pilots flying the two 182's were basically refusing the fly the airplane WITHOUT the Madras tips, and were arguing and quarreling about who would get stuck with the "stock" wingtips model. He ended up buying the second set of tips to make everyone happy. Thats how impressed these pilots were of the low speed stability of the aircraft with the Madras tips.
Charles