massagewarehouse.com...you can buy gallon jugs starting at around $40. Gallons last a loooooonnnnnnnngggggg time.
It depends what you are looking for, whether you choose oil, lotion, or gel. I personally use gel. It is slicker than lotion but lasts longer/goes further than lotion or oil. Try all 3 out and decide from there, some people like oil and some hate it, same with the other choices.