How much does Premier Agent cost?
Premier Agent is a subscription: $49 USD per month, or $490 USD per year paid annually.
It is a flat subscription rather than a per-lead charge, so a busy month costs the same as a quiet one. There is no separate cost per lead and no allowance to run out of.
The subscription is bought on the portal for your market, at its /premier-agent page — see "Where do I subscribe to Premier Agent?". Taxes and payment methods follow the portal you subscribe on.