I suppose that works in a pinch. But, at $5 for a hundred pack, spaceballs don't seem overly expensive to me. If you use 8 per door, that's about $0.40 a door.
If caulk was packaged better, so it didn't dry out so fast, it might be a better deal. But, for the number of doors I build and the speed I build 'em, it'd be a $5 tube of caulk per door
Jay