First that comes to mind is dick Smith premium headphones. They sound better than average for inexpensive headphones but are not anything spectacular. There are dozen rebrands. Most priced between $20-50. I think pioneers version is most well known. Here is a picture of rock muma version.
Another headphone that surprised me with it's build quality is Marley ttr. Allmost everything is metal even the baffle! Plastic parts are covered in pleather which is also nice. Earpads are advertised as genuine leather. This is how you build a proper $299 fashion headphone! At current $35 price it is worth trying out. Sound is pretty good on active mode.
Then there is meizu hd50. About $50-60 and supposedly sounds very good. They also have biocellulose driver which is uncommon at this price range with the expection of CAL!.
My personal favorite for good build quality is Masters & dynamic mh40. What is not metal is covered in authentic leather. At $399 it is pricey but but luckily second hand prices are quite tolerable. Equally gorgeus on-ear version is a bit cheaper.
My favorite on-ear and portable regardless of wear type is kef m500. I prefer kef's sound over mh40, b&w p7, Solo 2, momentum over ear, oppo pm3, ML mikros 90, focal Pro&classic etc. I have not yet heard audeze sine or any of the b&o headphones.
Frame that goes around the pleather covered cups is magnesium
so it is like 60% metal even If The cups are not. Sony used magnesium on on sa-5000 and mdr-fi. Those are also lovely metal headphones but expensive+discontinued. Kef cost about $200 and are worth every penny imo
Other metal headphones that come to mind are aedle and California headphones. Msur n350 is not a metal headphone but uses wood for cups. Headband and hinges are metal. Priced at only $60 it deserves to be mentioned. I have the fullsize version n550 which is excellent. N350 has the same beryllium coated drivers so it is very likely that n350 also sounds better than anything by beats. Wood, metal, beryllium coated drivers, $60.