Yes, off the shelf. 7 1/2, and 8 is more common but #9 shot is still off the shelf available. I don't reload myself but others do. I've not tried the dental floss trick and it might not work of course, but I like to experiment as much as possible rather than guess and take gun writers' word for things.
www.CheaperThanDirt.com has #9 Estate Shot for $3.95 a box listed. They also have #8 and #7 1/2 listed in Estate -- the least expensive ammo they have.
There is also Magnum 2 3/4" #9 in Heavy Load for lots more money.
They also have PMC ammo in all the above shot sizes in 2 3/4" AND they have a Remington Heavy Dove Load which is a fast and heavy load of #8.
Lots of Off The Shelf choices.