Powering an APA102 LED Light Strip
If you choose to power a full 3 meter string from one end with one large power supply, you're going to have voltage drop problems I think at the other end and I think you're PCB traces will be hotter than you want if you drive them at full.

I suggest cutting the power and ground trace after each segment of 144 LEDs and powering each of the three segments with a separate 50W power supply.  Just cut the PWR and GND traces of course...leave the data and clock lines intact. 

The IRM-60-5ST from Meanwell is perfectly suited and you can buy from Mouser.

I have a feeling that the real world current draw from the APA102C is lower than the datasheet says when driving white (level 255 on all 3 colors).

Please post your real world current for driving 144 of these at full.  Will be interesting to see.  Maybe you can get by with a smaller power supply after all.