If you're ultimately going to re-locate the tower, I would go the DIY method.
Really, the only difference between a mini fridge and a kegerator is the tower (which may require relocating the cooling line), and having the extra crap that is part of a fridge just not built in, and then shipping the extra stuff.
All you'll need if you go the DIY method is a fridge, co2 tank, regulator, tee with shut off valves, some line for the gas, some line for the beer, ball locks and/or other taps for your beer, a tower and some faucets to go onto the tower. Quite often you can find this stuff as a 'conversion kit' on morebeer and other home brew stores. Drill a hole into the side of the fridge, run your beer lines to wherever you have your tower mounted and off you go. The only thing I might be concerned about is the length of the lines which will allow the beer in the lines to warm up.
As far as which model, no idea... I bought the prebuilt one. But unless the ledge is really that big, I can't see it being difficult to get two cornies in there, and you can set your co2 tank on top of the ledge, the thing's going to take up room anyway.