I think it's a safe bet the extra zero is a typo. What I find disturbing is charging twice the price for the Golden set because of the "additional bonus". It's not an "additional bonus" if you're charging twice the price and I already have Hero's Forge. If you want to sell a package deal, do that separately. Also, apparently most of the mounts are about to disappear from the marketplace? That's...not really a happy announcement.
It's because of the cost of the Golden Hero's forge ornaments from the way you could previously attain them. It was based on referrals, and those folks spending (I believe) a combined amount of $200 in DBG cash. So for those who set up all of the accounts for referrals, and spent the SOE/DBG cash, that's roughly what it would have worked out to.
I personally maxed 3 accounts and got one of those to 37/25 and was working on a 4th and I still think these prices are absolutely outrageous and way too expensive for fluff.
If you were going to charge that much for armor it should have been Player Studio designed. ugly armor for an ugly price.. no thanks They only suckered me into the uber expensive expansion version for TMB beause my toons name is Corwyhn LIONheart and my guild is LIONS of the Heart and heck it was a flying LION! But hey if there are people with the money to spend on this stuff go for it...I won't miss the armor. I would probably be throwing in heros forge on both sets that that price though.