Need to power 4 star mount LEDs
DO NOT wires your LEDs in parallel. Since all LEDs have a bit different voltage drops, the one with the lowest voltage drop will hog all the current, then burn. Then the next one will hog the current... etc.

Put them all in series. This way you only need one 150mA current source.

Your digikey link doesnt work, so I'll use your Vf data. For 4 LEDs in series we have:

min 20V
max 32V
typ 26V

So you need a 150mA constant current supply which can supply an output voltage between 20 and 26V.

There are lots of ready-made units for LED lighting. Check here for example:

http://www.meanwell.com/product/led/LED.html#non

If you cant find a 150mA one, pick a dimmable 350mA supply and dim it to 150 mA...