Kogan are selling all variants of the Steam Deck. Appears to be the first major Australian retailer to sell the Steam Deck though there are other marketplace sellers if you want to roll the dice on warranty. Press Start has a roundup of some cheaper alternatives here. The 256GB price is approximately $100 more expensive than a VPN/US card/post forwarding solution that works out to $891.25 AUD based on Shipito (Oregon tax-free) and Mastercard exchange rates. That $100 might be worth it for people who want Australian warranty and to avoid the complexities of shipping it yourself (your mileage with Kogan warranty may vary). Also keep in mind the extensive self-repair options.
If you are holding out for a local stockist, bets are EB will stock it with similar price to the US (based on Valve index sales) though there has been no announcement. Also the AUD is expected to climb against the USD this year.
A gaming NUC like this with steam big picture mode would be better for your use case. You should also put Windows on it for better game compatibility.