Are you building your own raised garden bed? If you have a plan drawn up, we would love to see it. I recommend using a 200 x 50mm 2.4m H4 Micropro Sienna Pine Sleeper. It is ideal for landscaping, garden beds, parks, and children's playgrounds.
Let me tag our experienced member @LePallet and see if they have other timber recommendations for raised garden beds.
My other recommendation earlier was Cypress timber and as you mentioned is currently not available at the store. My suggestion is to call around your local garden stores and see if they have it in stock.
We look forward to seeing your garden bed project.