None of the Android's are anything compared to the N900... that is why I'm getting one.

But, keeping in mind your general user all three are more than adequate for what they need. And the Cliq is really not bad compared to the N-One.

So using your numbers, over a span of 24 months you save approx $456.

The Cliq and MyTouch can be had for about $150 (at least, when I bought my wife the Cliq) + contract. With the N900 at, we'll say $500 - then I guess over 24 months you do save about $100 (if you were a first adopter at closer to $600 you about break even). However, for an unlocked iPhone at $800 you don't save anything.

If you decide you hate t-mobile and switch then you actually limit the usefulness of your phone and can either live on a new carrier on the sub-par EDGE equivalent network; or you get a new phone for that carrier that fully advantages 3G. In this scenario, whether you saved money or not is going to depend largely how long was left on your contract - as most carriers now reduce the buy-out charges for every month you are on the plan.