Google Geocoding has usage limit of 2500 in the free API. I have two questions
Is it possible to make payment for additional requests ?
How much is the Maps for Business package ?
As per my experience, I used it in one of my projects, the limit is 2500 request / 24 hours, this limit is free and you can't exceed it unless you contact them for higher quote, I believe cost will be same as the Google maps which is $0.5 per 1000 request or may be you can get better price with higher quote.
Google Geoconding: Free up to 2,500 requests per day $0.50 USD / 1,000 additional requests, up to 100,000 daily
Google Maps: Free until exceeding 25,000 map loads per day for 90 consecutive days $0.50 USD / 1,000 additional map loads above 25,000 per day after reaching 25,000 map load / 90 day usage limit, up to 1,000,000 daily
more details: https://developers.google.com/maps/pricing-and-plans/