Getting a gigabit link with a competent IP-transit provider will be on the order of 3 - 5K$/month. Thats 1000mbits 24/7 not limited by how many bytes you push through it.
A switch and router for your rack stacks will be on the order of $15K (that's a couple of 48 port GbE switches and a Cisco router (or equivalent))
You really need to understand the depreciation costs. As your equipment ages you will need to replace it (if only to keep on supported platforms). $100K + $30K for servers + $15K for networking gear is $145K of gear. If you squeeze all you can out of it and only replace it in 5 years then you can do a 5 year straight line depreciation so add about $30K/year to your costs for depreciating the old gear.
On the storage array, if you want 10TB of raid protected storage with the MD1220 you need 24 600GB SAS drives [1] which comes in at $23K each (not $12K)(oh an you have two of those and you again have $10K/yr depreciation).
Oh and you probably want a service contract, something like onsite in 4 hrs or if you're a bit more laid back in 24hrs. That will add another $150K/year ( but I'm sure that you can get the sales guy to knock off a bunch as its probably a list price vs 'what i can get it for' kind of deal)
Another real world bit that will bite you is that while you can "fit" all this gear in a 40U rack you can't put enough power into that rack at a Colo facility to run it. The servers are 750W machines, so lets say you put a 120V/30A circuits into your rack, you can really only draw about 25A before people complain so you have about 3KW/circuit available. A 'normal' colo facility will offer you 2 per rack. So with 750W servers you can run 8 machines per rack. You'll probably not run them that hard and can get away with maybe 12 per rack. But with 54 totals servers that is going to be 5 racks minimum and maybe 6. (remember your switch and router will take power too). Either way you're looking at 24 - 30 'circuits' for this space and those are probably about $500/month each so another $12-15K/month in 'power+cooling' charge.
You pretty much have to add in either the cost of a tech or half the cost of one of your operations employees to run this setup. Ideally you have two people at half time so that you can structure vacations for them. So put it down as one full time sysadmin and one full time tech, implemented as anywhere between 2 and 4 people. Don't forget to include the cost of their office space, their health plans, and their laptops :-).
Did you include travel time and travel expense? So most things can be 'lights out' but many exceptions to that rule exist. If you can drive to the data center from home then you're better off than if you have to fly there and check into a motel.
All that being said, its an important exercise to run through and figure out the costs since it is your own money that you are spending. And AWS does get some economies from being able to fractionalize things like sysadmin resources.
[1] http://configure.us.dell.com/dellstore/config.aspx?oc=bvcwmk...