I will give you one concession and that is that the employee wasn't able to give you any information about the mattress you were looking at. If he did not know he should have found out.
Now to the shocking.
Basically what you are upset about is that the employee dropped the price. He went from making money, to making less money, to making even less money, etc. It is every businesses goal to make a profit on what they are selling. It sounds like he gave you a considerable price drop and to my knowledge not one that can be done on a regular basis. He might have been short of a monthly quota and instead of him getting paid he was trying to take one for the team earn your business and offer you a pretty good deal. Your dealing with a company that has approx. 430 stores. That is a significant number and one that is not attained by screwing people over.
My other question is if you needed your wife to make a decision why were you there in the first place without her. I don't walk into a store unless I have the ability to by something at that store. I am not saying don't be a consumer and shop around by any means. All I am saying if you are going go to have your wife there with you. How would you feel if I showed up and wasted your time?
Better yet, how would you feel if I showed up wasted your time and then blasted you on a rip off website about you giving me more than half off? Pretty inconsiderate. It is his job to ask for your business. Why would he go to his area manager and get an additional discount for you when you can't buy anything anyway it just makes him look like a bad salesman which he very well might be if he can't tell you about the mattress. It is amazing to me how you can critique someone without looking at it from their perspective.