Several Nokia models offer changeable faceplates. You might not be able to buy the phone in all-white, but chances are, if the model you puchase has changeable faceplates, they will have one available in white. You're not limited to Nokia, either. This is just the Nokia forum you've posted in. Other brands offer changeable faceplates, so that's what you need to keep an eye out for when you're shopping phones on t-mobile.com or ebay.
Try using phonescoop's phone finder to select features that are important to you (like changeable faceplates) and you will be able to view a list of T-Mobile phones that match up to the features you want in your new phone.
http://www.phonescoop.com/phones/finder.php
Hope this helps
