The one I've seen talked about the most is the Dell 28 Ultra HD 4K (1) and it is indeed 30HZ.
1 - http://accessories.us.dell.com/sna/productdetail.aspx?c=us&c....
1 - http://accessories.us.dell.com/sna/productdetail.aspx?c=us&c....
Dell makes plenty of high end monitors, they just don't give them away at loss-generating prices.
The 3008WFP-HC (not 4K) is a 30", 2560x1600 monitor, 30 bit, S-IPS panel.
I'm not sure why anyone is surprised that a $400 4K monitor is not running at 60Hz. It's not like Apple would offer that? You're right. But their solution would also not be anywhere near the same.
Hell, they haven't even updated the Thunderbolt Display. Even today, it requires a MagSafe to MagSafe Adapter to work with ANY Macbook currently on sale (seriously, Apple? You can't replace the connector with MagSafe 2?) and doesn't support USB3.