I buy mine from allstitch. They are $10.25 for 100 needles
I use Schmetz or Organ. They can be found in bulk on eBay at a fairly good price. I just browse eBay and buy when I find a really good price. I won't use Titanium. I have a friend who had to have a piece of a shattered Titanium needle surgically removed from her arm. That made my decision for me. I know there are those who love them but I don't want to take a chance. With my luck the shard would find something vital..like an eye.
I can't tell you where to get needles, BUT there have been some discussions about the titatium needles. Seems they can break into several pieces when they DO break. As you are supposed to change your needle often, I'd stick with the regular type. I did have a titatium one break & it went into 3 pieces and flew all over the place.