Overlaying Text Labels on X-Axis and Y-Axis?

Hi,

What would be the best way to overlay a text label on the Y-Axis? The use case I have is that I am displaying a real time chart for a stock and I need to also show the real time price within a text label that overlays on top of the Y-Axis (price axis) and moves when the price changes. I have looked at both annotations and category axis but they both don't seem to be the right solution for this and I wasn't sure if there was anything obvious that I am missing.

Mark