If your boss wants a little attention then give her some. General pleasantries should be enough. Talk about general things and pop culture. I understand not wanting to get personal at work. Give them a few bones to chew on, like going to a movie with your sister, going shopping with your mom...
How do you know they are coming from the same distributor? Even if they are they may still be getting a different price. I buy supplies for my department. Depending on the amount of supplies I buy I can sometimes get a discounted price, or I've just happened to buy at a time when the price is...