Complete/Near Set Builders- Toughest Card?

[Kawika]

I have put together a few pre-war player sets (as distinguished from master sets - I don't have the jam for errors, variations, traded cards etc - if all the players are represented, I'm done).

D304:
Most Difficult: None impossibly tough. Tenney has that reputation but I saw at least a couple available after I got mine.
Most Expensive: No surprise here. Cobb. Matty, Wags & Young pretty spendy, too.

T3:
Most Difficult: Rhoades and Bransfield were supposed to be the toughies. Didn't have a hard time with Rhoades but have seen very few for sale. Bransfield seems to come around on a regular basis.
Most Expensive: Cobb again. What is it about that guy?

T209-1 Contentnea Colors:
Most Difficult: Probably Lane and Bourquise. Never, ever saw them until I won a lot with all the remaining cards I needed at one go.
Most Expensive: I'd be guessing here. Maybe Martin. He is one of your scarcer cards and as good of a poster boy for Contentneas as you'd want.

E97 C.A. Briggs:
Set still in progress. Kinda hot right now and any that show up besides the BIN dregs command crazy money.

Most Difficult: Maybe Hemphill, maybe Keeler.
Most Expensive: "Cy" Young. Never mind that the player depicted is Irv Young. Most sellers fail to make that distinction. It's a nice card; love to find a cheap one.