It's bad strategy to set your buy limits at a round number, like Craig did. Much better to set at $1.51-1.53, so your order gets filled. Too many people will put it at the large, round number and it will sometimes drop to numbers like "1.51" and then go back up.
PS - For flash crash reasons, and information transmission reasons, I do not suggest using a stop loss.
It does vary sometimes depending on support levels indicators, but your point has been duly noted. Many thanks @lexconical :)