Cards numbered 175, 186, 203, and 209 are super hard to find...
In all seriousness, these numbers do create havoc on your binder organization...I bought the "cards that never were" fantasy cards to fill the holes which was kind of fun.
Nothing to hard to actually find, all readily available except as mentioned specific grades for commons will be hard to track down unless subbing yourself. Gil Hodges, Willie Mays, Yogi Berra, and Duke Snider all come at more of a premium due to being in the "high" numbers. The Harry Agganis can be tricky...sad story and I believe this is his only card.
Beautiful classic set, one of my favorites...and at 206 cards the commons won't break the bank too bad...have fun and good luck!