What Thunderbolt to USB 3.0 cables/adapters exist for OS X and Mac hardware? I have the Late 2013 Macbook Pro, which has two USB 3.0 ports and two Thunderbolt 2 ports. I currently use both USB 3.0 ports and one TB2 port. I want to connect a third USB 3.0 device to the machine, but I don't want to use a USB splitter on one USB port as I'm concerned the devices would draw too much power from the bus. I have no current use for the second TB2 port and I would love to be able to use it for this purpose. 

Browsing extensively online, I've found numerous docks, such as Belkin's Thunderbolt Express, that connect via a Thunderbolt cable. This would work, but it's an expensive, 'bulkier' solution (and not the one I'm looking for). 

I'm aware that a USB 3.0 device wouldn't be able to take advantage of Thunderbolt's I/O speeds, but it's certainly compatible, which is all I'd need. After all, Apple even sells a Thunderbolt to Firewire Adapter. I also know that Thunderbolt is not only used for digital video purposes (along with the TB > Firewire option, there exists Thunderbolt External Hard Drives). 

There are almost no Thunderbolt to USB 3.0 cables/adapters on the market. I'd think this hardware would be more prevalent given the prominence of USB devices out there. What adapters are available for OS X?
As a matter of fact "Kanex" the only company I know of that offers "true" adapters put their Thunderbolt to eSATA + USB 3.0 adapter on the market 18 hours ago, at a price point of 69.95$