Interruptible (spot) instances are cheaper but can be reclaimed by other users.
Critical Note: When using vast.search_offers(type='bid', ...) to find spot offers, you must pass a bid_price to vast.create_instance(...). If you omit bid_price, the SDK defaults to renting the instance at the on-demand price (dph_total) instead of the interruptible price.
If you are outbid, the instance moves to a stopped state (it is not destroyed) and storage charges continue. You can resume the instance by increasing your bid using vast.change_bid(id=..., price=...).