We have friends a little like that, except that there is a significant difference in our incomes. Great people, but a little on the cheap side.
For example, one time we had some DVC points to burn so we made an OKW trip during Christmas break. They would not go to Disney parks because of the cost, only Universal. And the stayed only one night with us in a 2 BR because of food and activity costs (they were paying $0 for lodging). Needless to say, we haven't considered taking any more trips with them.
When we go to dinner together, we have them pick the restaurant so we won't be out of their price range. We always order at least one appetizer for the table, usually two. They split their entre.
Still, they are great people and some of our best friends so we just smile and move on. The friendship is worth much more than a few minor annoyances.