given that steel is an inferior frame material, i assume you're looking at these for a particular reason, like a vibe, or the ability to do custom geometry? If i wanted a steel frame, i'd probably look locally for a boutique builder, if not an outright welder if you know your tube shapes. On alibaba the seaboard frames are almost free, whatever price you see on alix is going to be in LARGE part just shipping.
Or get a Peugeot 2nd hand or something like that from a million years ago?