Depending on:
1) Where you are
2) How long you want to extend it

I'd recommend this stuff: https://www.adafruit.com/product/3892

It's 4-wire, but just peel off one of the wires to make it three. It's beautiful to work with, very flexible and the insulation doesn't melt with over enthusiastic soldering. Adafruit can do good shipping out of NYC and there are distributors in many parts of the world. That pack is trimmed to 1 metre, so if you need longer, it might be awkward.