Yes, there's a limit. The maximum bid is 100,000,000 gold coins (100kk). No bigger bids are accepted. This also means that the first player who places that bid is guaranteed to win the auction (because it is not possible to outbid that bid).
Golden Post of SeptemberPosted on Wednesday August 29, 2018
Golden Post of September - final resultsPosted on Saturday October 06, 2018