Overall, the online resources for the Desert Eagle are kinda thin given all the attention the pistol gets.   Looking to put together a collection of them and am interested if certain models and calibers are more desirable than others.

Would be some interesting info!

You might give Magnum Research a call.  When I bought a Mark I back in the late 90's I called them to see when it was imported.  Talked with the Vice President.  He had to go down to the basement and get some of the original paperwork, cause, turned out, my gun was one of the first 1000 imported in '85!

So, if he was willing to help a guy over the phone like that, maybe they have that info tucked away on a website or a pamphlet or something...

Best information I have found from here:  http://www.americanrifleman.org/articles/desert-eagle-50-review

Production History
The Desert Eagle was first conceived in 1979, and became the founding idea behind Magnum Research, Inc. of St. Paul, Minn. The goal was to create a gas-operated, semi-automatic pistol capable of firing magnum caliber ammunition. Its basic design was patented in 1980, with working prototypes completed in 1981. Final touches to the pistol were completed under contract with Israel Military Industries (IMI). The earliest variant to go into production was the Mark I, first available late in 1983 and chambered in .357 Mag. With the design finally perfected in 1986, the Desert Eagle premiered again as the very first successful semi-auto handgun chambered in .44 Mag.
The physical characteristics that demark the early models are the single-step slide release, the teardrop-shaped safety lever and the absence of an integral slide rail. The Mark I made its film debut in 1985 in the hands of Captain Stanley White, played by Mickey Rourke, in the movie “Year of the Dragon.” That same year, it was further popularized in the movie “Commando,” starring Arnold Schwarzenegger. Though the Mark I is the dominant model in movies made prior to the 1990s, it has continued to make appearances in more recent films.
The .357 Mag. chambering represented just the first step in the Desert Eagle’s history of continuing enhancements and improvements. In 1987, the pistol was chambered in, what was at the time, the innovative .41 Mag., although it is no longer in production. By 1989, the Mark VII model became the next standard for the Desert Eagle. All subsequent pistols contain the changes to the Mark VII, which include a two-stage trigger, an enlarged slide release and a re-designed safety lever. This is the model most likely to be seen in movies during the 1990s. Film appearances include “Predator 2” (1990), “Harley Davidson and the Marlboro Man” (1991) and “Escape from LA” (1996).
It was in the mid 1990s when the Desert Eagle became a super star, in more ways than one. Magnum Research released the Desert Eagle chambered in .50 Action Express. Once thought to be an impossible handgun to build, this was the first .50 caliber semi-auto to reach the market, and the only one still in production. It was during this time that the Mark XIX specifications were added to the design. This involved the adoption of a single-size frame for all calibers in order to allow for quick caliber conversions. Trading out the barrel, magazine and bolt allows the Mark XIX to shoot the full range of currently available calibers, from .357 Mag. to .50 Action Express. The Mark XIX update also includes one of the most noticeable changes, an integral sight rail.