You can try going to a place that sells them in bulk for rental parties, weddings, etc. You can also usually find large jugs at the dollar store.
My kids always loved bubbles too, so you can always make a mixture from liquid dish detergent and water them down a bit. Shake it up really well and you should get lots of bubbles! A liquid dish detergent landing on furniture or the carpet shouldn't hurt anything.
I think it's a fun thing to do for Paw Paw and it shouldn't make much mess.
I have family in Bristol, so a shout out to Tennessee from us.