The poor nations of West Africa work on a cash economy. All the French-speaking countries of West Africa use the CFA (African Financial Community) franc. Larger towns like Diapaga and Fada N'Gourma do have ATMs (cash points), although they may not be on your card's network. When you do find an ATM, withdraw the maximum amount. Then put away your credit cards and your traveller's cheques, because you will use cash exclusively.
Oddly, there is never any change. If you buy two hot, fresh doughnuts for 25 francs, the vendor will cheerfully take your 10,000 franc note, but will not be able to give you change. Shop first at the larger stores and pick up all the change you can, to use at smaller shops, street vendors, and the market.
ATM/cash points limit on what you can take in one transaction. There is also a limit on what you can take out in 24 hours, determined by your card issuer. Call your credit card company in advance and ask them to raise that limit to, say, $1,000/day.
Also tell your credit card company you will be making large withdrawals in odd places. Otherwise they may put a hold on your entire account when they see something unusual, leaving you with no source of money.
If you arrange your guide in advance, and you trust him, you can send him money. Bank-to-bank transfers should go through as long as you know the guide's bank's Swift code, his account number, and the full bank routing number. Otherwise Western Union is dependable.
In a pinch, get on the Internet, go to westernunion.com, and send yourself money to pick up anywhere in whatever country you're in. It is usually cheaper to charge a transfer to a debit card so you don't pay fees for the cash advance. Western Union charges about 10%, xo to send yourself $900 will probably cost you $991 plus any bank fees.
Costs are generally low, certainly much lower than in most of the world. The park lodgings range from $30 to $75 per night, double occupancy. Of course AC or a ceiling fan is more expensive than a canvas tent! Food costs are also low. In the cities, although pizza or steak frites may cost a Western price, riz sauce and grilled chicken will probably be under $8.00. Beer is cheap, but imported wine and spirits are not.
Tipping, while always welcome, is not usually mandatory. Nice gifts (including cash) for your driver and guide are always appropriate.