Travel in West Africa - Safety and Visas

Prices, processing times vary wildly based on embassy.
Benin: (safety) Transit Visa (48 hours) at border: $20
With transit, can go to Cotonou and get 30-day single/multiple for $24
Burkina Faso: (safety) Available at land borders and airport: US$18
Cameroon: (safety) In advance, quickly issued in neighboring countries for US$60
Chad: (safety) In advance, 30-day for $100
Equatorial Guinea: (safety) No visa required for Americans!
The Gambia: (safety) In advance, 2-3 days, $45 for 30 days
Ghana: (safety) In advance, 30-day $24
Guinea: (safety) In advance, 90-day, $25-$50
Guinea Bissau: (safety) Airport or in advance, 45 days US$60
Ivory Coast: (safety) In advance, one-month visas US$54
Mali: (safety) At border, 30-day for US$27, or embassy for $36
Mauritania: (safety) In advance, three-month visas cost US$70 ($7 in The Gambia?)
Niger: (safety) Cost about the same as combo visa ($50)
Nigeria: (safety) Need sponsorship - except in Accra, Niamey - 30-day visa, $100
Liberia: (safety) In advance, US$100 for US citizens, single-entry one-month
Senegal: (safety) No visa required
Sierra Leone: (safety) Available at the airport and land borders, $100/$150 for 30-day single/90-day multiple
Togo: (safety) 7-day at border for $20
Combo Visas: Visa Touristique Entente (Benin, Burkina Faso, Niger, Togo and Côte d’Ivoire) - $50 (60 days, one entry each, only sold in Ouagadougou, Niamey, Cotonou?)