I used the Inspeed on, but found it became unreliable and started under-reading after about 6 months. Have just ordered a pro anemometer kit from Windlogger. It looks to be well made.
I use a Madgetech logger - it can go right down to 1 second readings, or longer periods if you want it to run for longer.
We also have a logger from Windlogger (above) which records onto an SD card.
I would caution against relying on this entirely to give you an estimate of the income from a wind turbine.
Anemometer cups get pushed by the wind, regardless of turbulence levels, whereas turbine blades are more severely affected by turbulence.
Good luck with it. Quentin.