Depends how much money you're willing to spend and how light you want to go.
For me personally, I'm using vintage Cannondale panniers onto an Axiom Journey rear rack.
My camping gear consists of a 3.5lb solo tent, 2lb sleeping pad, sleeping bag + inflatable pillow(on its way), and some other things. One rear pannier will be for camping related gear, the other pannier will be for personal belongings. All in all, I will have less than 40lb of gear onto my bike.
How much did I spend? Well, the panniers I got with my older Miyata, but the modern stuff (in $CAD):
Axion Journey rack: $50
MEC Spark 1 Solo tent: $300
MEC sleeping pad: $90
Sleeping bag + pillow: $40
I'm probably missing something. But the rule of thumb is, the lighter you go, the more expensive it becomes.
I chose panniers because I'm working with what I have. A long saddle bag was out of my budget.
If you're interest, I can post a picture with my setup so you can get an idea of how it looks.