PSU with dc stepdown buck
Make sure the driver states that it is constant current.  If they say that they are, and have an adjust (potentiometer) for current, it's likely that they are constant current.  With the links you provided, it looks as if 3 of them are constant current capable, while the remaining 1 isn't.

If you have doubts about if it is or isn't capable, you could also look at the datasheet for the regulator's controller chip.  In many instances of my purchases of these types of regulators off of ebay, I've noticed the designs are not far off of the reference designs in the datasheet.

An additional note is, you might want to run lower than the rated max current on your LEDs, until you know how much heat you'll be putting out with both the regulators and the LEDs.  That might help you iron out kinks and keep it from being a "smoke project".  You can always turn up the current later.