This operator can help select your international flights, but you'll have to book them yourself help
Fly to/from Kilimanjaro Airport (JRO - Check price) near Arusha. Or fly to/from Arusha Airport (ARK - Check price) via Dar es Salaam or Nairobi (Kenya)
A transfer from and back to the airport is included
Additional accommodation before and at the end of the tour can be arranged for an extra cost
I went on the two day budget safari to Tarangire and Ngorongoro. As a European it was a bit hard to get used to the fact that business was handled via WhatsApp. It was hard to initially accept the legitimacy of doing business like this....