Factory 219 is hard to come by and precious. If you do not handload, now is a great time to get into it. Brass can be turned from 25-35 or 30-30 brass which are both readily available and relatively inexpensive.
There is little flat or round nose bullet selection available, but if you don't mind one in the chamber and only one in the magtube, there are spitzers out there that make the 219 one heck of a varminter.
I got a 336 in 219Z too about 7 months ago, with the bull barrel, and I just recently got done with some starting loads but I have yet to get to the range to see how they perform.
Rifleranger is correct, if you want to shoot your zipper on a regular basis reloading is the only way to go as any ammo you purchase will be expensive. That said, the old west scrounger does load the 219 zipper, but it runs about $30 a box.