Wow, I thought you'd be mortified! Instead you don't consider it "unethical in the slightest" because you thought it was the only way you could win.
How much money do you think you made from your review which was written to make it seem like you weren't affiliated with the product? However much that is is what you sold out for.
My opinion: Friends and family is above the line. Reviewing yourself or paying people is below the line.