Well, nevermind. Rebar sure looked cheaper, but I'd have to spend around 130$ on enough rebar to make 3' stakes where I can get enough wooden stakes for around $50. So I guess here's a different question.
My boards are going to be 2' high. I have 2 stake options. I can get 1.5"x1.5"x24" stakes and pound those down 12" every 2' around the perimeter. Option 2 is to get 1"x2"x36" and pound those down 12" every 2 feet. My only concern with option 2 is that the stakes are thin and I'd be afraid they couldn't hold up the board strength. So what's more important? Having the stakes flush to the top of the boards or having them 12" down from the top but being thicker? I suppose I could also pound the stakes in so that the 1" length is flush with the board, and the 2" comes out perpendicular for more support? Thoughts?