Hannants vac pac models??????

[Oasisscott]

Does anyone buy the vac pac models from hannants/Welsh models? They seem to have lots of models that you can't get anywhere else - like Nimrod, E3a Sentry, the new RAF rivet Joint . Why are they able to provide them and not other major model companies? Also what's the difference between vac pac and resin? Are they the same to build as normal
Styrene kits? Want to be sure as I know they are more expensive but j don't mind paying if it means j get to build the rare kits I so long to have in my collection!!!