Nice Saying To Put In Wedding Card Should We Buy A Wedding Gift For Someone That Owes Us Money?

Should we buy a wedding gift for someone that owes us money? - nice saying to put in wedding card

Several years ago we showed you the money friends. They have paid a little behind, but we still need about $ 1500 and has been for 2 years I have given nothing. They have the money because they always buy the latest anything. If we recall, are all "Oh yeah, like they forgot or something!" We realized our mistake, and the money is gone, the friendship has changed, this is not the problem further, I'm more of her!
The question now is whether to marry the couple. My husband is the best choice and will probably also asked to organize themselves (and pay) a part of the baccalaureate.
How then to justify up to $ 100 (the usual) wedding gift? How do I tactfully handle this? A map? Purchase price of certain gift, but does not cost anything? Put a note on the card, he said, to report, it is our gift! I'm sorry that they have been disrepectful not pay us, but I handle it with maturity.
Thank you!