I believe that Ra's al Ghul, no slouch in the dollars department, back in the '70s discovered Bats' secret identity by tracing what chemicals Batman must have been using to the original purchaser. ("That's a hole I'll plug" said the Batguy, always one to learn from experience.) It wasn't stated outright that it took money to uncover this info, but one assumes that costly computers and/or generous pay-offs were used.
