Re: Is it paid monthly?
YouTube campaigns are similar to search or display campaigns in the sense that you manage your spend through a daily budget which gets spent according to what you bid on each keyword or placement. The amount it costs you every month depends entirely on how much you allocate as your daily budget, how much you bid on your placements, as well as the type of bidding that you use.
I would suggest that a better strategy for you is to create a campaign with a budget of the amount that you are willing to spend and then see how many impressions you get from that. From there you can adjust your budget accordingly after a week or two of running the campaign.
Let us know if you have any other questions about this,