It used to sell for 350k until this rumor hit the mill. Look at the items that give treasure hunter. We're talking dozens of millions of gil-equivalent assets. Assassin's gloves. Thief's knife. That's all.
All these other items...mandy leaves, lucky eggs, desks...they're charms. Nothing more. Can't hurt to have them, but I'm going to roll my eyes at you if you're a L40 rdm thinking you have TH4. Now I won't make fun of people who keep these items, but for the record none of these items even remotely hold a candle to official TH items in terms of difficulty to get. Do you REALLY think square is going to let a blm get TH2 for 850,000 gil? Th3 with a silly mandy leaf that drops like crabapples for me in yhoator? Th4 with a lucky egg by the time they hit boyhada tree?
No. To get TH4 you have to wear 40 million gil and a Dynamis-Xarcabard drop in your hands as a L75 thief. There is no TH5, 6, 7, and 8. If there were, the desk would drop off Vrtra in power mode only.
Don't waste your money on a Millionaire's desk unless you want to pay for what it says it does. Because it does what it says it does.