User blog comment:Jimeee/Skyrim 1.9 beta update adds Legendary difficulty and raises level cap (Updated Apr 8th)/@comment-101.114.147.51-20130409033821/@comment-63.230.63.225-20130410003528

I have found that once a merchant has 30000 gold, they will not provide any gold when traded with. They will still take your gold though.