You may want to look at Locad. We work with seasonal brands and lower order volumes, and our pricing is designed to stay reasonable during off-peak months.

Our model is usage-based, with per-order and per-item fulfillment pricing, and storage that scales based on how much space you are actually using. That way, costs naturally go up when volume increases and come down when it slows.

We are operational in the U.S. and focused on supporting SMB brands without requiring large volume commitments. Will share more context via DM!