"Protect your investment" sounds way too "high pressure used car salesman" to me. I don't like the way it sounds."Protect your investment" is a powerful statement to the customer as most purchases must make financial sense.
Also we walk a very fine line of being high pressure used car salesmen without being high pressure used car salesmen. The best tactic to upsells is Giving them the option, Explain why the option makes sense and is needed to give it validity then they will make an informed decision. If that doesn't work break their knee caps with the carpet rake