Voluntary work with lions and monkeys in Africa (Luanda)

I am a great animal lover and would very much like to realize my dream of doing voluntary work with lions or monkeys in Africa. I've seen a few projects in South Africa, Kenya and one in Zimbabwe called Walking with Lions but they're all quite expensive asking for around Protected content for 2 weeks. Do you know of any project I could participate in where I get to care for lions or monkeys (or even better, both!) at a more affordable price? Who can I contact?
I'd be extremely grateful for any information you could give me.

Thanks

Carla