The 3-9X40 and 3-9X42 are very different scopes. The 3-9X40, regardless of who's name was on it has been the budget scope in the lineup. Not that it is a bad scope, I like 'em a lot. I have an original Zeiss and 3 of the Cabelas branded scopes. I can confirm that they are all the same scope except for the badges.
The 3-9X42 has always been considerably more expensive. I don't know what makes it more expensive, but I do believe they are made by different manufacturers. I think the parts for the 3-9X40 are from Eastern Europe and assembled in the USA. Not sure about the 3-9X42 but they are not made by the same manufacturer. With optics price is usually a pretty good indicator of quality. A $800 scope will always be better than a $400 scope. It may not be twice as good, and the $400 scope may be more than good enough for the job at hand, but the more expensive optic will almost always be better.
But regardless of that, the 3-9X40 is as much scope as I need. I bought 2 of them from Cabela's when they closed them out $250 and a 3rd one used. I have had the Zeiss branded scope for at least 10 years.
The 3-9x40 and 3-9x42 are considerably different scopes, but not sure why you state they are from different manufacturers. They are different scopes. Period. I found the 3x9x40 version to be superior in terms of ergonomics, eye relief/eye box, and reticle. I haven't used the 3-9x42 version, but have a couple of the 4-12x50, which have the same rear ocular design, so fair to assume similar scopes optically. So far, I don't really see a huge advantage or difference optically of the newer style meopros to the older style. The price increase probably has more to do with being the newer, current style over the older style.
All that being said, if you're referring to the Cabela's change from the Instinct (older style meopro) to the Euro Instinct (newer style meopro), at least that's how I think I remember it, then I think it's a reflection of the update to the newer style. The most recent scope (I think it was called the Instinct HD) had a wrong description on the website, and it was manufactured by whoever makes Vortex. There was a substantial jump in price (and drop in quality in my opinion) when they changed suppliers of their house-branded optics to Vortex.
