Hey Chris, you can make custom maps with Mapbox but you don't have to - here's a look at our core styles + designer styles that come out of the box, https://www.mapbox.com/help/studio-manual-styles/#mapbox-tem.... Pricing is based on transactions for each API. Lots of folks find this table helpful - https://www.mapbox.com/help/account-faq/#what-api-requests-d....
Note - I work at Mapbox
https://www.mapbox.com/api-documentation/#styles