Beyblade X has landed in Aus! So far they can be found at Kmart, Target, Toyworld, and EB Games.
Target is the cheapest option at $14 for a booster, $19 for a starter, $25 for a dual pack, and $89 for a stadium set.
The rest of this guide can be used to find beys that are not yet available here.
This video has a good rundown on the different types of products.
Best option: Paxbeys
Paxbeys is a store run by a member of the community with the aim of making beyblades available for the cheapest prices.
Best for stadiums: Suruga-ya
Suruga-ya frequently has free shipping sales (they'll tell you on the main banner on the site when its on). When these are on it's a great way to get Beyblade X beys in Australia, and the only way to get X stadiums for a reasonable price. However they are often out of stock.
Stadiums are now also sold on Amazon.
Cheap option: Aliexpress beyblade stores
Aliexpress has a lot of fakes on it, but I've put together a list of four stores that as far as I can tell sell legitimate beys, and for a good price. I haven't bought from any of these myself so I can't verify, so I recommend looking at the reviews for people who have.
Best for bulk buys: Ever-Wish
Ever-Wish is one of the cheapest options overall and has a wholesale option with cheaper prices when you buy at least 2 of the same bey, good for buying together with a friend. However, beware of USD conversion when shopping here. Example price: 1 booster and a set of 3 boosters without boxes cost $90 including shipping.
In-store option: Popuanime
Popuanime is the only place in brisbane that I'm aware of that sells Takara Tomy Beyblade X, a booster there will set you back $25 and a starter $32, however no guarantees they'll have any in stock.
Australian seller: Megaculture
Since they're local the shipping will be far more reasonable, however a single starter at this store will set you back $45.
Hasbro online: The Gamesmen
This site sells the same Hasbro beys you can find in big retailers, but they sold the collab beys way earlier, and for $35 instead of the $45 that EB Games was selling them for.
My personal recommendation is to buy from department stores if they have what you're looking for. Aliexpress will have most products available, and has the cheapest shipping. And Paxbeys is the best option for pre-ordering new beys, and as a community run store it will often have a good selection for competitive play. Stadiums can be bought on Amazon or Suruga-ya for about the same price ($80-$90).