This may have been asked a billion times, but why is it that 29ers are generally more expensive than other equivalent 26" wheel bikes?

I'm looking to add an MTB after years of roadie-ness and commuting, mainly just for banging around fire roads/carriage roads and doing the odd bit of singletrack near where we've just moved (lots of great trails, not so many great roads to ride on immediately nearby)... I'm tall, I'm not doing crazy technical stuff, and preferred the idea of a 29er, but am perplexed by why the same exact bike spec-wise is so much different in price the moment you add in the bigger wheel...