I tried doing the same thing, and know your frustrations all too well.
I think what's different with this series is that Topps didn't put a puzzle card in every pack, only every 4th one I think, so you don't have the usual abundance of checklist cards and that's why you're seeing the stickers sets offered without puzzles, and the complete puzzles going for a bit more than you'd expect. I broke down and picked up a puzzle from cardgarys, he's been the only one listing complete puzzles consistently.