Around here (Illinois) you can find small canisters of helium for home use. I think they are about $20.
Are there party supply stores near you? Those tend to have regular balloons but with a less permeable material that holds helium longer than the real cheap ones you buy to blow up with air. Our grocery stores often carry those kind of balloons also in the floral department.
In my experience, US grocery store bakeries often have balloons and helium on hand. They often fill balloons to go with the birthday cakes they make. If you’re only interested in half a dozen, that might be the easiest way to do it.
If you wanted many balloons, I would suggest buying a party-sized helium tank from your local Wal-Mart type place.
As Chief Pedant has indicated, standard balloons don’t hold helium especially well - you should probably figure on a couple of hours of decent buoyancy. So unless you can get from the balloon store to the party reasonably quickly, the “U-inflate-em” tank could be a good idea.
thank you, everyone! I think I’m going to go with the grocery store option… the point really is to just have them for a few hours in order to announce to the world that it’s her birthday and decorate her presents and stuff.
She lives a few hours away and all the festivities are taking place in and around her parents’ house (close to me)… so it’s better for them to become garbage before she drives back because then she won’t want (or feel obligated to) stuff them in her car and take them with her.
Since the OP is answered, here is a MPSIMS comment:
Then she will miss the opportunity for a cool physics demonstration:
Tape the string of a helium balloon to center console of a car, so that it just clears the headliner and dome light. Note the motion of the balloon when the car brakes, accelerates and corners. If you don’t find this cool, then you really must turn in your nerd card.