There are 3 Types of "durable" Material
Type 1: Strong to its End: Any good ol' Fiber or Carbon reeinforced helmet. They will take some heavy blows but when their time has come they gone FUBAR and the bucket must be replaced (cause its cheaper then to repair)
Type 2: Konervative Strong: Any handcrafted Metal Helmet like Blowtorched Steel Like this or bolted and glued handdished alloy for Example They will take many blows and can be easily fixed with a Hammer and some hot glue. But is more tricky to craft.
Type 3: Expandable Strong: A Helmet so cheap and easy to make - you can put it in the trashcan and make a new one within a Weekend. Like (klick the pic) for example hand bended PVC-plates glued and bondo'ed to an old motorcycle helmet.
If you want to modify it: You can either stick with buying a "standard" helmet and put some stuff on it. Or you get yourself a Pepakura file of a standard-helmet, build idt on your own and put your stuff on it. It depends on how much you would like to modify - a good Jango or Boba helmet only pays the less you modify them. The more Stuff you put on and well, you may got cheaper if you just craft it your own in the first place XD The best way to start would be a Sheet of Paper and a Pen, and draw your thoughts black on white.
