How much should I spend on educational board games?

Calculate cost per play
A game used 50 times over two years costs half as much per play as one used 25 times. Before buying, estimate honestly how often it will actually be played. A game that sits on a shelf costs infinitely much per play. Buy fewer, higher-quality games that genuinely interest your group.
Entry-level vs. lasting purchases
Small games (card-based or quick ruleset) cost less and work well for testing whether a group enjoys a genre. Larger boxed games with varied components cost more but offer more depth and replayability. Neither is wasteful if it matches your actual usage patterns.
Secondary markets extend value
If a game stops holding interest, selling or trading it secondhand recovers part of the cost. This makes a higher initial investment lower-risk. Many board games hold resale value reasonably well for several years.
Quality over quantity
Three games played regularly teach more than ten games gathering dust. Spend less overall by being selective about what enters your collection.