need i remind you the sand in shika's timer? [img]i/expressions/face-icon-small-wink.gif[/img]

besides, if he can only use the sand in his gourd.....then he'd be screwed.....just consider all the times where he probably left at least a little bit behind (like when sasuke was pursuing him, he saw a trail of sand)
eventually he'd run out

and if you've seen gaara's final form.....i dont think he'd have even 1/100th of the sand it must take to form that.