I am not a salesperson and by understanding is that pricing is a Black Art, but here is what I know:
Organisations are weird and full of conflicting incentives and dumb politics. Selling to organizations consists of navigating this stupidity. How do you draw your map? Well, here are a few guiding questions:
"Who is in pain?" -- Which person or group of people in the organization is feeling frustrated or blocked by not having your solution? This person, if you collaborate with them, can be your advocate within the organisation.
"Who signs the cheques?" and "How big is their pen?" -- Certain people have the authority to make purchasing decisions, usually up to a certain dollar^(or other currency) amount. You want to find out who these people are, which is not too hard. You ideally want to figure out the dollar amount, but that is basically guesswork. The key is that if you are talking with a staff member who can sign off on $200/month and you charge more, then this staff member will have to go up to her boss and get approval. Otherwise, the staff member can just decide that the product will save them money in the long run and decide to buy right there.
"How much is it costing them?"
There is a technique called SPIN selling which I don't actually know but I think the jist of it is that you find ways to quantify the pain of not having a solution to an organization and to show that purchasing your product is cheaper than the alternative.
Question for the rest of the folks here: How much should OP plan to on charging for ongoing support/bugfixes/security updates?