I buy mine through Amazon, too. I like Temco best, but you will find other brands. 32ga is what is used in most common atomizer coils, but you can wind more turns with 28 ga to arrive at the same resistance. Sometimes, it's good to be able to wind a smaller coil with more turns to get lower resistance and cover more of the wick. I use both 32ga and 28 ga.
Check out Rip Trippers on YouTube for good demonstrations of re-coiling almost any atomizer head you'd want to use.