Two sources where you can get cut edge subway tiles. One is
http://www.subwaytile.com/ I just did my kitchen with this tile and was very happy. Caveat with SubwayTile is that they prefer to work with contractors/professionals instead of DIY home owners. Another source is
http://www.restorationtile.com/subway.html They may be able to match what you have color wise.
One thing to watch out for is the thickness of the tile. I had samples from both sources and there was a difference in the thickness. Not a big deal for me but if you are trying to match it is something to look out for
Just as an FYI, here is the tile in my kitchen
Diane