Across my toons, between 150k-400k. Love the feature and always make sure to get my favourite sets for my toons. I can afford it without a problem though so it's no big deal ^^.
With buying sets from the AH the figure probably goes up even more. Purchased 4 sets that are boe which I am keeping in my bank alts bags until we get more space overall since my mains bank and vault = full. Also got the Glorious plate for my paladin.