Q: How much does Maxmind's service cost?
A: You can purchase "credit" at a cost of US$0.0001 per query
Example: US$25 gives you 250,000 queries; US$50 gives you 500,000 queries; etc
Q: Why not use one of the free IP databases?
A: Be careful about accuracy and keeping your dataset up to date - ownership and usage of IP ranges can change. This addon does not support using other data sources, as I prefer to use Maxmind's service which costs very little to use overall and I know it is kept up to date.