Seedream 5 Lite still, then Seedance 2.5 clip: $4.67 for 8 seconds

Making the first frame with an image model and animating it with a video model costs about $4.67 on Sume for an 8-second 9:16 clip: one Seedream 5 Lite image at $0.04375 and one Seedance 2.5 job at $4.63. Both are ByteDance models, and the still gives you a cheap place to fix composition before you pay for motion.

Three stills to choose from cost $0.13 in total. A bad first frame is a 4-cent mistake; a bad video take is a $4.63 one.

The pipeline, priced

Hand-off between the two models

Generate the still at 9:16 so the frame already has the video's shape. Seedream 5 Lite is priced at $0.035 list on Sume's Image Router, so $0.04375 after the 1.25 margin. When the image job finishes, its result carries a public media.sume.com URL; use that as the first_frame in frame_images on the video request, with resolution and aspect_ratio set explicitly.

What the still can and cannot do

The still fixes the look but not the motion. Describe the motion in the prompt and leave the scene description out; the frame already holds it. If the person or product in the still must stay identical throughout, add a last_frame or reference image of the same subject.

A different image model works the same way; the reason to use Seedream is price and one vendor family, not a quality claim. Compare a few stills from other models before you commit a series.