My mom found me the other two tins on her side of town today. Millennium Falcon, X-Wing, Vader's TIE, and Death Star make up the set of 4. Three different regular boxes, Vader is the front of all three.
I've tracked down all the boxes, but was unaware of tins. On the subject of cereal, it looks like there is Cinnamon Toast Crunch, Reese's Puffs, and Cheerios so far.
The only place I have found the tins are Wal-Marts. Each one only seems to have a couple. By checking all the ones in my town I found the set in mint boxes. $4.97 each
The tins are Walmart exclusives. I heard them mention this at their booth at Celebration. They were give away tins and shirts if you thumb wrestled at their booth. Sadly did not have time, as you had to sign release forms so they could record it, and I had other places to be.