The original 1978/79 editions through the 1984 reprints (PHB art by David Trampier/DMG art by David Sutherland III) or the 1985 and subsequent reprints (art by Jeff Easley)?
Regardless, WOTC would hold the copyright to those works, so if they aren't selling art prints, nobody is.
I've seen art prints for the Easley paintings off-and-on over the years, but I don't think I've ever seen those originals.
I seem to recall reading that a lot of the original art pieces from the early days of D&D turned up missing and/or were accidentally destroyed when the TSR offices moved to a bigger location in the mid-80s. I know that Erol Otus ended up having to re-create a number of his classic pieces since the originals were gone and high-quality archival photographs of his work had never been taken. It wouldn't surprise me if the same happened to the Trampier/Sutherland paintings.
And Sutherland died in 2005.
Oh, and I have two t-shirts, one each with the original covers of the AD&D DMG and AD&D module I6: Ravenlopft, but I later learned that they were bootlegs: The company that made them didn't have the rights to the artwork, and had been working from scans of book covers.