I am a broke person with mostly-broke friends who has attended a lot of weddings in the past few years. Usually I buy one of the cheapest things on the registry and send it with a personal note, since the importance of the gift to me is the gesture. (If the cheapest thing on your friends’ registries is still too expensive, that’s a different problem.)
But I am also a somewhat-recently married person, and in that respect, can I implore the people who don’t bring gifts to please still give a card?? I still remember which of my friends did not give us gifts…not because I care about the gifts, but because it is awkward and confusing to not know whether a sent gift was misplaced or never received. I want to make sure that if you gave me a gift, I’ve sent you a thank-you card! And if I’m not sure whether you gave me a gift or not, there is an awkwardness underlying interactions even years later. I don’t want you to think I’m ungrateful because I never sent you a card for a gift I didn’t receive…but I definitely can’t ask.