Hi Shane, and welcome to the wonderful world of online sales, and of course to SaleHoo : )
Ozgunner has given you some pretty solid advice there, but regarding DH Gate, yes.....a stack of fakes. The safest thing to chase when dealing with any Chinese supplier is off branded items, stay well clear of anything with a brand.
DVD boxsets are unfortunately almost all bootlegs, I suspect they all are, but I'll just say almost as I'm not 100% sure at this point lol.
If you are wanting to sell the type of stock you are talking about, look toward the UK and Europe inn general for suppliers, the UK nd most areas throughout Europe are PAL, and will work on Australian and NZ consoles.
Good luck with it : )