Where are you and what are you going to use it for?
I can give you an address but it won't do much good if you're in Kilimanjaro. Look for a local chem supply house and pick it up. If you have to have it shipped, count on paying an extra $20 and up for hazardous fees.
(AAA) - ALWAYS ADD ACID to water. NEVER add water to acid!
Concentration will depend on your use.