Innodisk just announced that they are coming out with a 4K capable M.2 form factor GPU. But according to this site, it won't be available until the end of January.
The manual for the J3160TM lists these 3 options below. All of which are good reliable brands.
DELTA DELTA-ADP-150TB-150W/19V
HP HP-TBC-BA52-150W/19V
FSP FSP-FSP150-ABAN1-150W/19V
It looks enoch just dropped their pricing on Innodisk 16GB VLP 2666MHz M4UI-AGS1WC0K-C to $169.40. Its not $150, but it is a lot better than it was. I have been watch this site for awhile now, waiting for the price to drop.