MTK makes, assembles, and paints sandy lids. I don't know what you're idea of "cheap" is ... But it would be an option. Other than that, I would suggest buying an ATA kit and building/painting it. The second way is more fun.
J
They are in the ROTJ section on StarWars Helmets.com ... ROTJ Helmets used more than one style/kind of Mic Tip. Also, some of the ROTJ helmets were reconditioned ESB helmets, so they still had the HOVI style tips. The metal ones were shaped like this:
The helmets that still had HOVIs in them did. The rest ... I don't think so because they were a different design. The screens were heavier gauge than the ANH HOVIs.
I took a photo (and traced) my SiMan helmet padding ... originally I did it to make accurate padding for my Mini Stormtrooper helmet. But the original (or full scale) is 17" across.