I use photocopier paper boxes with gorilla tape around the box and lid. You can store 100 bagged and carded comics in each and they are stackable.
Went into Gosh in Soho ( I bought loads in the 80’s when they were near the British Museum) last week and picked up a Neal Adams 1969 Detective. They’re getting expensive to fill the gaps nowadays.
Batman, Detective and Brave & Bold with Joker are always expensive.