BuyDig has open box 6-foot Marseille mCable Upscaling HDMI Cables w/ 4K Ultra HD Video Processor on sale for $7.99. Shipping is free.
At least this time they are selling them as open box closeout. Last time they forgot mention the open box part.
I believe the main reason that Marseille stopped this line was due to that they advertised this model including on the box for video and gaming. But this one doesn't work so well for gaming. But it is great on video so long as you do not get one that looks saturated. You can even just get one and use it with a multi-port 4k HDMI switch.
Now they offer a cinema and a gaming mCable. It turns out they couldn't get one cable to do both satisfactory. So, do not get this model and expect it to work well on all gaming. But with that said people did report on the $15 deal thread that in some instances it did help with gaming. Just depends on the signal you are sending through it.
They work great on streaming devices even if your tv is 4k capable. It even worked on my Nvidia Shield to 2017 4k TV. If you use one on the Fire stick or 3rd gen Fire tv 4k you will also need a HDMI coupler. Like below.