Kourou, French Guiana
I stayed in Kourou with a local friend for several days and he set me up with a cheap ride back to St. Laurent.
He said the best way to get affordable transportation in French Guiana is to use the internet to find drivers who you can carpool with. Due to the high price of gasoline in French Guiana, this is very common and accepted means of transportation and the price is much cheaper than a taxi. I believe he used the Craigslist and Carpoolworld websites to search for transportation.
*Our driver did not speak more than a few words of English so you may need a translator to confirm price, meeting point and destination.