Sorry, I just saw this and I had to come play devil's advocate.
Your entire premise (and the adage itself) assumes that eskimos live in winterland all year round, which is untrue. They don't live in igloos, their snow melts every year, and they probably already buy ice for coolers, ice dispensers and such.
Now selling lava would be impressive, not so much because an eskimo is concerned about things melting, but because you would need to capture the lava first and then be able to keep it in a molten form.
Once it's a solid, you could sell that to anyone. Who doesn't want a lava rock? That shit is awesome.
ILE
7w8 so/sp
Very busy with work. Only kind of around.