I'm looking for data points to check changes in $z$ as the Earth moves towards and away from a star. I'm finding lots of data for various objects  but lots of variation too (for eg, the results for M31 are quite varied from -230 to -330 though perhaps that's due to the many moving parts within M31 that could be the source in each measurement?).
I was wondering what object I should be looking at if I wanted a simple example showing how we can verify Earth's velocity around the sun using spectroscopy, as it's a value we can also calculate by other methods as around 30km/s. I'm guessing ideally this would be a star in our own galaxy that is close to lying on the plane of Earth's orbit around the sun. Measurements over time could be used to check that the only variation in $z$ correlates with Earth's orbit.
Are there tutorials or similar showing how this can be calculated? (It sounds like a good tutorial question to help people learn)
Edit: Updated to clarify question.