BEST WAYS TO TELL EMPLOYEES "HEY, YOU DID A GOOD JOB"

I have a staff of three, and they have been busting tail for two weeks on a high profile project, coming in early and staying late. I'd like to show my appreciation. I have no budget for this kind of thing; it'll be coming out of my own pocket. So I'm crowdsourcing ideas here. Add your ideas as suggestions or vote your opinion in the comments.
  1. Email to my boss to make sure she knows how much they've been doing, to which she will probably respond with a thank you email to them and will probably copy her boss on that. Everyone will know how much our department contributed.
    This will definitely be done.
  2. Nominate them all for Staff Member of the Month
    None of them will be chosen since there will be three people nominated for the same reason, but they'll get a certificate and recognition at the next staff assembly just for the nomination. This is free.
  3. Gift cards inside handwritten thank you cards.
    I did this last year for a similar situation. Hurt my wallet a bit, but worth it. I didn't get much reaction from them about it, but everyone loves a gift card, right?
  4. Bring in lunch to celebrate.
    Seems nice to me. Also, bonus points for being a team bonding activity and being less expensive than the gift cards.
  5. Time off
    Is it possible to let them go home an hour early (or more) and beat rush hour or take care of errands or start an early FAC?
    Suggested by   @andersun