Sabatti is probably the cheapest at reasonable quality, and IIRC you can start getting into those for about $5k. But for the money, Blaser's S2, IIRC, is close to that and likely to be of much better quality.
Interested to hear who has a double barrel rifle and wether or not they feel the expense was worth it? I am years, as in probably 10+, from ever going to Africa but plan to make it one day. Part of that dream is hard to detach from having a large bore double barrel rifle. I would love to hunt...
I have a Sabatti in 45-70. It's one of the funnest rifles I own. I do wish that i would have gotten a a 9.3x74r as that caliber is a lot more versatile.
For an entry level, if you get a 9.3x74r, they are usually several thousand less than a rifle in a Nitro Express caliber.
I would also look at Chapuis rifles. You can consistently purchase one of their rifles in the $10k range for a NE caliber. These are a lot better than a Sabatti. These rifles do have a sharp comb that smacks me in the cheek. That's just my experience though on a 470.