Start with something realistic that you want
Then move onto something you'd get if you won 20+million AUD lottery money.
Then you can make jokes about Tardis' or Airships or dinosaurs or whatever.

I want a Suzuki Swift as my next car if my current one ever fails me.

I'd get a Jeep Wrangler if I was a millionaire so I could go on all sorts of adventures. Also a Toyota Corolla for safe reliable non-adventure driving. I think I'd just always worry about a super expensive car being stolen.

Maybe I'd also get a helicopter lisence