How do I choose the best topsoil for a raised garden bed in Courtenay????

So, I’m planning on building a raised garden bed this summer, and I’m totally lost when it comes to picking the right topsoil. I’ve heard that the soil you use in a raised bed is super important for healthy plants, but how do you even know what’s good? Should I just go with what’s cheapest, or is it worth spending more on something that’s better quality? Any advice on what kind of topsoil works best for raised garden beds???