Most recent promo thread announcement.

Forever Love Puppy Mask:
2013: 1,750 energy
2014: 1,900 energy
2015: 3,000 energy

Crest of Love:
2013: Unavailable
2014: 3,800 energy
2015: 3,200 energy

Love Aura:
2012: ???
2013: Free with energy purchase
2014: ???
2015: 3,500 energy

Heart Eyes:
2013: Unavailable
2014: 3,500 energy
2015: 3,800 energy

Red Lazy Snipe:
Non-event: 293,730 crowns
2015: 3,200 energy [268kcrn at current market price]

Red Wandering Snipe:
Non-event: 425,600 crowns
2015: 5,000 energy [420kcrn at current market price]

I was hoping to pull all the information from the wiki, but ended up having to google-fu some forum threads and found a couple logs. Just missing Love Aura's 2012 and 2014 values.