I'm looking for a good number of sandbags to fill up to stop incoming...flood water.
Wish/wonder if you could buy those ... big sand bags ... last a long time.
... You could make anything you wanted out of those things
Well, he only wanted to stop incoming water so bags suitable for building "anything" aren't what he wants.
If he did, I could have mentioned the "earthbags" used by the enviro-conscious crowd to build a variety of things. Information is plentiful and there are how-to vids on Youtube for every aspect of using them. According to the info I've found, they're poly and cost about $75/500. They're also meant to be sealed inside walls and not left out in the sun.
Let me google that for you