These are only "rare" because they are just coming in and some stores had them street dated for 4/6 up until recently. Now as more stores get them in, they are becoming increasingly common. Given the fact they had special packaging made, one can assume they will not be uncommon in the near future. After all, every variant for Swap Force so far can still be found on shelves or online at retail with a little effort.
Springtime Trigger Happy is indeed that way in game, we saw in game images of him as well early on, way before the figure was shown. On the 3DS version, you can go to the museum and see every "in game" figure.that will be released for this game. Jade Fire Kraken and Kickoff Countdown are the only variants left now unreleased (along with LC Bumbleblast and Doom Stone regulars). This is the fifth unique in game version of Trigger Happy, by the way.
Fryno is just regular Fryno, and shouldn't be hard to find. He is in the current regular assortment in normal packaging and consumes a third of each of those cases (4 figures). That means he is actually double shipping. The only appeal of the Spring version is for the Easter packaging, good for the basket.
Punk Shock, however, is going to be a little more difficult for now, her regular single won't be out until next wave - so the Spring version is the only way to get her until the next wave - likely late April/early May at minimum. Honestly, they have kind of gone lazy on the water figures, she makes the third "mer-person" they have released (Gil Grunt, Riptide and Punk Shock), the second ranged one with a gun.