He Owes Me A Favor, But He's Cashing In

Dear Mongoose,
Recently, I did a pretty big favor for a guy I know who is a contractor. I didn't have to do it, and didn't do it so he'd owe me, but it was something that let him profit a great deal. When I needed a small project done, I called him, hoping he'd return the favor. Not only did he not give me any discount, the price was actually higher than I thought. Should I bring up the old favor I did for him or just pay the bill and do business elsewhere the next time?

Dear Jilted Samaritan,
The ole saying goes; 'no good deed goes unpunished'.  One of the best parts of doing a favor for someone is the feeling you get from knowing you just did a good deed. If one does a favor or good deed hinging on the anticipation of reciprocation--you're doing it wrong.  I'm in the 'take it on the chin, pick up the pieces and move on' camp. Karma will eventually kick in and this contractor will get what's coming to him/her/ze (supposedly a new gender neutral pronoun). Judging by what you've written ze (there's that word again), is probably a crummy contractor anyway. 
​-MG