I paid for our wedding and couldn't afford a sit down dinner. We had hors d'oeuvres and cookies in the church fellowship hall. Oh, the horror!
I've been to weddings like that, and they tend to be a lot of fun. Been to some where the families cooked and served the food, etc..
You spend what you can afford, and the wedding gifts usually more than pay for the cost of the wedding anyway. This bride may have had a strategy of inviting people, asking them to pay for their meal, but still expecting them to give a gift if they end up declining.
Be pretty funny to offer them a gift but ask them to pay for it.