I charge:

$20 for the first one hour introductory lesson

$20 per half hour. 30-45 minutes is recommended for children under 12 and 60 minutes works best for older chikdren and adults.

$45 per full lesson for semi-private, (for two people.) You need to bring the friend though!

As a note, I would recommend a semi-private full lesson over a private half lesson as you will both benefit from the increased time.