I am trying to understand the true cost of adding a T1/E1 line for 
small and medium size business.  I understand that there are a number
of costs associated with this and would like to understand the following:

1.  What are all of the costs that I should consider when adding a T1/E1
2.  Detailed information on costs of:
     - Monthly Service Charges 
    -  CSU/DSU price per month (leasing)
    -  CSU/DUS price per month (purchase)
    -  Installation Charges 
    -  Contract Requirements
    -  Maintenance Agreement (if I require 24 x 7 support)
    -  Estimated Taxes
3.  I would like to understand how these costs vary between regions
(U.S., Latin America, Europe & Asia)
4.  Lead time required for provisioning.  (How long would it take for
me to get this service)
5.  What type of throughput is given (Mbps) with this service.  Are
there SLAs (service level agreements)

I realize that the prices can range widely between carriers and
countries but I am trying to understand the full picture.

Finally, please cite the source of the information (journals, etc).

A T1 is by definition 1.54 megabits per second. Depending on your
provider, you can expect to spend between $500 and $800+ monthly for
service, depending on various features, including CIR (Committed
Information Rate), and out of band (read: analof modem attached)
monitoring by the provider.

What is needed: a central office (CO) near enough to pull fiber to
your point of service. A router with a CSU/DSU to convert the raw T1
to 10/100 network. Provisioning can take from a week to a month or so,
depending on availability of fiber to your point of service.

But, all of this information is available for free from different
providers... Each country has different availability for provisioning
and different tax structures.

This is a free comment. For a paid answer by a researcher, perhaps
narrowing down the geographical listings to a few key areas will help
them to provide exactly what you're looking for. You seem to know what
you're asking about, so I would guess that you're looking for
something a bit more specific in your answer. If I may add anything
else to this, I'd merely suggest that you obtain a source for cisco
routers with the T1 interface on your own, so the price is fixed
regardless of provider. There is a reasonable expectation that nearly
all T1 providers will be happy enough to use a standardized router
config for their provisioning. However, also be aware that some
providers may be able to throw in the cost of the router in their
monthly fee, if you sign up for a specific time obligation.

Also, you want to be certain that your provider has an "out" clause...
some of the ones with whom I have dealt do have us under contract, but
still provide a 100% satisfaction guarantee that allows me to cancel
the contract if the performance isn't as specified.