I've been selling researched capital component blueprints for nearly three years now, and it's a fairly regular occurrence for somebody to contact me about one, usually asking if they can buy it for just a little less. These people are scammers. I've never gotten a legitimate offer for a blueprint.
Recently I was once again contacted by somebody, but instead of wanting to pay less they want me to get in touch with them to negotiate a price for moving the blueprint to a different system before they bought it. Obviously they were going to try a gank, so I moved it in my blockade-gu without trying to negotiate a fee and set up a contract for jita price.
They accepted the contract, then sent me an extra 70m for moving it. For surprising me I sent back the 70m plus all the blueprint profits.