The Amherst campus bus stop is at the Lee Loop, which is right outside of UB Commons. Buses operate every half hour during weekdays and have other schedules during weekends. There is no charge. Air The Buffalo airport has nonstop connections to major eastern destinations. Through the hub-cities there are connections to other destinations.
International connections are best through Toronto.
There is a bus service from the Marriott hotel to Toronto airport. The bus ride lasts about 4 hours. However, check first whether you need a visa to Canada.