^so it's like the Silverton of The Far East?
As for the OP's inquiry, I have Spats. Love 'em. Addmitedly I've only ridden them a total of 6 days, but those were six great days.
The downsides to them are that they are heavy and noodly. But once plunked in deep pow neither of those traits are apparant (they are only noticeable when hiking in-bounds with them on your shoulder or when hitting a hardpack groomer and watching the tips flop frantically).
The upsides? They float. They pivot. It's like driving a forklift in that you can turn on a dime, gain speed, scrub, slarve, smear, and slide to your heart's content.
If this is truly a deep only ski, then totally go for something with reverse camber.
Spats are the OG planks.
But folks like Praxis and DP have put some improvements into the mix (stiffer flex, a little more sidecut).
If you wanna keep it under $500, then Praxis or used Spats.
Other super wide possibilities (though I haven't ridden any, just heard good things) are:
Birdos Puder Luder or Floater or Eleven
DP Lotus 138
There's others, but most will prolly be outside of that $500 range...
btw, the Duret Monstre Pow is only 549 Euros...http://www.duretskis.com/index.php?idarticle=288
(they also have the Monstre Fat, which I believe is the widest ski in production at 177mm in the waist).