Here is a simplified example. Bing API is $7/1000 queries. Most users with HN pedigree search 100+ times a day. A single search for an error message can produce 10 follow up searches. That is $21/mo+ just in API cost a month. And we have lot of users hitting 200 queries/day limit (imposed in beta), so they would be hitting $40+/mo in API cost alone when we go live. This is cost without factoring infrastructure costs, other operating costs and salaries.
In order to have a hope of becoming sustainable you need to make a calculation that with a certain number of users you can break even.
In order to have a hope of becoming sustainable you need to make a calculation that with a certain number of users you can break even.