Manu Park or Puerto Maldonado?

[Maya]

We are going to Peru in April and would like to visit the Amazon. We heard Manu Park is absolutely amazing but is it true that you need to book a tour in advance? The guided tours I've seen online are extortionate (over £1000 per person for 6 days!)
Can you book a local tour from Cusco?
In case this is not an option, we were thinking of going to puerto maldonado. Has anyone been there? Is it a proper jungle experience (i.e wildlife and rainforest walks) or is it just being on the outskirts and not seeing too many animals?

Would love to hear any other suggestions!