Here is the list. About a third of these aren't cheap at all, such as "Take a moonlit walk on the beach." That will depend on where you live.
Others are too easy, such as the gifts of dark chocolate. I make sure the house is always full of dark chocolate, no matter how mundane the day. "Kiss in the rain" is a good idea, though one must contrive to be out in the rain. The stupidest might be: "Recreate your partner’s favorite romantic movie scene." Can I do Tarkovsky? Would it be better if I were supposed to mimic Tom Hanks?
Love notes are a good idea, but the general danger is inflation of meaning. After a while the notes don't carry the same wallop of emotion.
One strategy is to outrace the inflation of meaning with bigger and grander gestures each time. Another strategy is simply to give up. You might try to redefine the terms of the signalling competition, but good luck. In any case I view the list as better for seduction than the long-term.