See if any local welding supply stores have #14 or higher glass (or helmets) in stock. Some auto-shades can go that high, but many cap out at #13, and they're generally going to be >$300 for the ones that can darken to $14 or higher. If you end up using an auto-shade helmet you'll have to set the sensitivity and delay to their maximum values. Don't buy an auto-shade helmet that doesn't have these controls. It's also possible to stack a #10 welders glass plate inside an auto-shade helmet and tune the shade value to get to #14 if the auto-shade can't get that dark on its own. It should be impossible to see anything but the sun through the helmet + glass combination.

I got binoculars, sunglasses, and a camera filter at Best Buy. I had to have them ship the camera filter but it arrived much earlier than they said.

Here in South Carolina Lowe's still has them in stock in the local stores, though only as part of some "Eclipse Kit".