how does this helment compare to the $20 ones on ebay (from china?)
I've never seen one of the $20 ebay ones, but this is a legitimate helmet made by a legitimate company (HJC), rebranded by a legitimate company (Joe rocket, not quite top tier but definitely a major brand), and certainly sold for at least $100 in retail stores. You're getting the leftovers of a large purchase, and the most unpopular graphics design. The cool thing about a good helmet with a bad design is that you rarely see it
These helmets sold for $70 (a heavy discount) on this site previously.
IMO the only question is whether you'd use the $260 GC.