Not quite as low as the $0.27/megabit price in Riga. Hurricane Electric, a major Internet backbone, is coming to Africa. Although they aren't announcing prices, I predict they will offer much less expensive backhaul/transit. Most of the continent suffers from brutally high, cartel-like prices for wholesale connections. If HE prices as I expect they will, that could easily reduce consumer Internet prices by 15% to 35%. In turn, that will allow tens of millions more to connect.
In 2012 at the WCIT, a dozen Africans told me the high cost of transit/backhaul was by far the most important international obstacle to bringing the Internet to more Africans. A friend of mine was quoted $70/megabit for a Gig-E in Lagos last year. The cost in most European or American cities would be between $0.50 and perhaps $4.00. The current high price of backhaul raises the cost of a robust broadband connection probably $10-20 over what it could be. Even a second-rate service with a low cap is probably $5 more expensive than necessary.
There is a real cost involved carrying data 6,000 miles undersea but that explains only a small part of the 50-1 difference in the price between London and most of Africa. Most coastal countries are now served by more than one undersea cable.