Oddly enough, they are simply posters produced under the corporate name of a string of cinema draft houses across the US called Alamo.
Other than Alamo probably having access to a lot of movie poster copyrights because they are in the movie business, their only other advantage is being able to produce in large scale and on a variety of media [vinyl, canvas, et cetera].
Mondo also got noticed for producing poster graphics for the Academy Awards, a job much like any exhibit house or major imaging service might handle. This one, for instance,with the very unflashy website does a lot of work for the Smithsonian as well as U.S> government agencies and companies wanting trade show graphics.
If you look at their offerings you can get some idea of what type of equipment is used to produce these products. This can include lamination to substrates, overlamination, hanging materials as well as the actual printing o n a variety of surfaces.
Alamo/Mondo offers some of the same products either through it’s own business or through a subcontractor that produces graphics for museums and trade shows. At this scale the posters are not really cheap anywhere.
see Mondo’s blog and Alamo’s site [they seem to have originated in Austin.