I decided I wanted to get 4 copies of every Fellowship block card. I ended up spending $800 just on set 1 alone. To clarify, my original cards were lost/stolen around 2009 and never really built it back up other than buying a few booster boxes here and there when it was cheap. Fully $250 of that $800 was spent just on copies of
Goblin Swarms,
Goblin Armory,
Servant of the Secret Fire, and
Savagery to Match Their Numbers. Crazy how high some of these prices have gotten but it's worth every penny. Hopefully Mines and Realms won't set me back too much...
Btw I decided to only go for 1 copy of every Towers and King block card. The reality is if I ever get around to playing again in person, it will probably be Fellowship block exclusively. I may decide to get 4 copies of every Rohan and Dunland card in sets 4-6, since those were my favorite decks to build in Towers block and that would give me one solid deck to play with.
Any other very pricey (>$20 USD) cards in Mines or Realms I should be aware of?