They are only $90: http://truck-bedz.com/default.tpl?pageID=1&page=full&cart=1315697258702058&id1=36&id2=[id2]&id3=[id3]&--eqskudatarq=39%20%20VCSB%20T1

The $190 ones hold 4000 lbs: http://truck-bedz.com/default.tpl?pageID=1&page=full&cart=1315697258702058&id1=36&id2=[id2]&id3=[id3]&--eqskudatarq=19%20%20CSB%20T1   
I suppose this is so you can leave it inflated and pack all your gear on top of it.

We paid about $50 for a regular one in Moab.  That's with inflation... so it all depends on $$