We used to call this stuff unobtainium because it was so tightly controlled, but today you can buy it in many forms.
Titanium Metal Supply, Inc. is big on customer service, and they have no minimum order. If you have a project that would benefit from ultra light and strong material like titanium these are the guys to check out as a supplier.
They also provide information about machining titanium that would be extremely helpful to the uninitiated. Machining-Titanium-Alloys-Reference