Thats a tough call. You can make the creases go away, but it is retarded that they had to fold it just to keep shipping costs down. I dont think its worth $30 just so its straight when you get it. I think you can straighten it out good enough when you get it and then save the $30.
I also used more screws (about every 4") into the bumper to keep it nice and flush. That helped a lot too
I used the plastic factory plugs with no issues at all with mine. The material the spoiler is made from is very flexible. With time it will return to it's original shape.
As long as you aren't in a rush, no reason why you can't get it folded up