Tinkering with chemistry also motivated me to look for sources of hydrochloric and sulphuric acids, but in New York state the guy at the pharmacy said I needed parental permission. Wasn't gonna happen.
Sulphuric acid: No, hardware stores don't sell that here. You can get it from car batteries, and builders use the strong stuff for clearing drains. I have no idea how I could legally buy fuming sulphuric acid.
Nitric acid: Even less. Fuming nitric and sulphuric acid mixed gives you nitrating acid, which in turn is the gateway to nitrocellulose (and I suppose nitroglycerine), fulminate of mercury, and ghod knows what.
It's just as well that these latter two acids are restricted; if they weren't, I'm quite sure I'd have tried to make guncotton, and probably blown myself up.
The happily provided both... with a minimum order quantity of around 250 gallons.
And Duda Diesel sells a liter of 67.2% nitric acid for $60.43, or $101.69 for 2.5 (plus shipping ofc).