I can for sure offer up some links to some products, however there's a little catch when it comes to items I would offer up.
But before all that, any particular reason it absolutely has to be 3.1 and not 3.0? are you using a system with an NVMe SSD that has ridiculous read speeds and have a plethora of external devices that you are plugging in all at the same time that have the ability to write data at a rate that's faster than 5 gigabits per second?
Because if so, then yeah, 3.1 makes sense, otherwise USB 3.0 is all you'll need and you won't even be able to match the speeds that the connector and cable are capable of with most SSD's and plug in devices.
But if there's another more finite reason then please explain.
--UPDATE--
In...