Well if one could afford to buy a .577NE at auction trying to get cheap with the minor accessories would not make a lot of sense. This isn't a Boswell by chance?
Since the OP expressed concern about damaging the crown & or rifling during cleaning & did not specify that he wanted case accessories I suggested a site that stocks Parker Hale style one piece coated cleaning rods and jags & brushes in sizes up to .600 NE.
They aren't "cheap" but are the appropriate tools if you want to properly clean a big bore rifle. The break down rods that go in a case will work in a pinch but are mostly for "show & tell" as opposed to serious cleaning.
