Take a look around there are a few guys who make helmets all have differences...prices being one of them. Its up to you who you go with so research a bit before jumping into anything.
Do you need it soon or can you wait 6 ++ months? Most "accurate" is a Fettpride GMH. He does not paint them though. Hope this helps a little. Now for something similar to the mystery helmet you could try Bobamaker. He paints and finishes them for you so they're ready to wear. Take into consideration your head size if you're going to wear them. Research will be your best decision maker/breaker. Goood luck!
Helmet
ASOK MR Budget Helmet in Cold Cast Finish –
Arguably the best. It’s about 10% bigger than a real screen used helmet but if you are bigger guy then it will look better on you because Boba had “ bobble head” like appearance onscreen. Its scanned from a prepro helmet. http://www.thedentedhelmet.com/f23/fp-budget-helmet-cold-cast-40206/
Helmet
ASOK MR Budget Helmet in Cold Cast Finish –
Arguably the best. It’s about 10% bigger than a real screen used helmet but if you are bigger guy then it will look better on you because Boba had “ bobble head” like appearance onscreen. Its scanned from a prepro helmet. http://www.thedentedhelmet.com/f23/fp-budget-helmet-cold-cast-40206/