Sketchup-free is for personal use only and the Warehouse will only support it's own native format. With all its disabled features, it's really no more exciting than the demo programs you can download for any 3D app.

$1.99 for Hexagon may not be free, but it's a third of what I paid for lunch today and that's pretty inexpensive for a full-fledged 3D modeling program without any restrictions.

With less restrictions, Sketchup might be worth a try because it sounds interesting, but there's only so much time in my life to learn how to use modeling programs that I don't want to put much time in one that won't let me export what I create and, even if there were a way around that restriction, won't let me use it commercially.