Wan 3.0 Prime from a node on your own fal.ai key, from $0.068 a second. Wire two stills in and let it move between them on the canvas.
$0.068 a second at 480p, $0.14 at 720p, $0.28 at 1080p. You pay the provider; Flowgen adds nothing.
Your fal.ai key, or Higgsfield.
A prompt, and a still to animate if you have one.
Keyframe work. Feed it two stills you already like and it moves between them without inventing a third face, which makes it the safe choice when the frames were expensive to get right.
The jump from 720p to 1080p doubles the rate. At 480p it is cheap enough to block with; at 1080p it costs more per second than Kling v3 Pro.
The First & last frame template already wires it up.