It is honestly very difficult to find in Yaounde such offers. A furnished apartment implies that the owner pays the high price to maintain its real property, it is not very possible to have these offers as easily. The best may be to rent an unfurnished apartment and then to gradually fill with the equipment strictly necessary, but it is not possible because that means you need to rent long enough to hope to furnish your property on the local long term.
The best you can do is spend your money, stop dreaming! there are not many people who are willing to allow you to rent their homes cheaper, a house is still not rented out to lose money. It happens that some tenants benefit from the fact that they have paid for a home start doing anything in the home they rent. So why a person have to sell off his apartment? Especially here in Yaounde where money is increasingly scarce.
If you want to rent an apartment, take money and put you in the search