Rare does not mean valuable.
In 1969, Dodge made very few slant six powered Chargers. That same year they made a ton of 440 powered Chargers. Despite the rarity, the slant six cars do not demand a premium.
To get back into guns, the 41 maggie is a great cartridge. The Redhawk is a proven platform with an impressive fan base. However, the Redhawks chambered in 41 mag are more of an "oh, yeah they made those too" kind of gun for the shooting world. They only have increased value to the "one of everything" Ruger collectors and the hard core 41 mag fans.
The 41 will always be the often forgotten little brother of the 429 magnum.