I have not been to Tanzania but this is my understanding.

Unless you are quoted an all-in price, Tanzania has a number of fees in addition to the daily rates and trophy fees. Just an example from Wendell Reich's Website:

Masailand

Government Fees Price
Government Observer Royalty per day $50
Wildlife Conservation Fee/Hunting Client/day $100
Hunting License Fee for 8 days and over $600
Hunting License Fee for 7 days $450
Concession Fee per day $100
Dip & Pack Safaris of 7 and 10 days $1100
Dip & Pack Safaris of 11 days and over $2200

Other fees you might encounter (from a Selous page of Wendell's Website):

10%Community Development fees on animals killed or wounded
Charter or road transfer to camp from Dar es Salaam
Transportation from USA to Dar es Salaam
Hotel accommodation in Dar es Salaam on night of arrival
Additional gun licenses $150/gun

I am not sure if you pay a fee/tax on ammunition in addition to the gun license fees.

I am not sure that all companies charge just the minimum trophy fees.

I am not saying that all of these apply in every case. Get a firm quote that clearly spells out what is and is not included.