If you already reload .45-70, you're probably going to balk at the prices for Buffalo Bore. I can't imagine spending over $5/round for something I can load myself for $.50/round. If someone doesn't reload, that's different of course.
Even "cheap" .45-70 ammo is usually going to cost $2/round.
If you're looking for factory ammo to get the brass, just post a WTB on the EE. I snagged 120-140 once-fired cases for $40. Not a single short Hornady case in the lot.
If you just want a couple boxes of factory ammo to keep around, I've always found local stores to be much better than online stores. Online stores turnover is much faster because they have a significantly larger customer base. When something comes in, it sells quicker, so there is often only a couple different types of ammo in stock at the same time (at least for a less popular cartridge like the .45-70; relative to things like 9mm, .223, and .308).