jj79,
You did not pick a caliber that will be cheap to shoot a lot if you plan on using factory ammo. If you don't already reload, start. Reloading will save you more money than you can imagine.
If I were you I'd do a google search for 6.8mm ammo and see what that comes up with, then check out midwayusa.com, natchez.com, sportsmansguide.com & cheaperthandirt.com. You may also find great deals on components at gunbroker.com. I usually shop there for once fired brass.