First, internet transit is incredibly competitive. The protocols are designed from the ground up to support changes and redundancy in network routes, so there is not a lot preventing any company from switching ISP service aside from their contracts and the constraints of what wires reach their data center. Because of this competition, prices are always getting lower and vendors are constantly working to reduce costs. Geography is a very significant variable, of course: getting a lot of bandwidth in rural Idaho is going to be much much more expensive than getting it in New York, London, or Seoul because you won't have many options. The most expensive, of course, is in markets that are regulated monopolies; many African countries have absolutely ludicrous bandwidth costs for the same reason they are expensive to fly to.
On the bright side, though, ISPs are constantly working to make the network more efficient. One mechanism for this is peering, where two ISPs agree to exchange traffic that is bound for destinations on each other's network directly, rather than each individually paying their provider to do so. It used to be that only large ISPs would bother to work our peering agreements among each other, but over the past 10 years peer-to-peer traffic has dramatically increased traffic between different ISPs in local and regional markets, so those smaller guys have learned to do peering as well.
What does all this mean? I'm no libertarian, but it's hard not to be awed by the efficiency and power of the unregulated global internet. For whatever reason, tens of thousands of companies are working together around the world in an amazingly cooperative and efficient way, even though many of them are fierce competitors. We could certainly stand some of that in the domestic telephone market, and we'll probably get it eventually, if only because the cost of VOIP transit will probably round to zero within our lifetime.