Where can I buy/rent helium for balloons?

Most party places rent tanks. Use the phone book.

Malls, party store, etc.

My Walmart sells a helium tank. It is small not sure how many balloons it would blow up. When its empty you take it to the party store and have it refilled. Also in my town we have a rental business that rents everything under the sun-including helium tanks. Look in the phonebook and see if you have something like that near you.

Amazon sell small disposable helium tanks (filling fifty 9”, twenty-seven 11” or twenty-seven 18” round balloons) for $39.25.

Or you might want to try It’s a Gas depending on how many balloons you need to fill.

I’m sure you could find a provider in your area with a quick google, or as already mentioned check the phone-book.

if there is a Praxair near you they do…
here

You might be able to rent the tank but I think you’re going to have a hard time renting the helium.