your question are more suitable to ask to your own client, but let me try to help
do I host n8n for them? this is depending on them on their budget, explain that if they use their own n8n they will pay the server fee, but it’s their own, if they don’t want they can use yours, but ofc, that means a subscription based
What is the price?
from my experience, theres 2 types of pricing model, Buy once and that’s it, and subscription model
where you charge them first the setup fee, and then the maintenance fee for the recurring monthly