Don don't worry about it. Your hourly rate is what your time is worth to you. that is all that matters.
If you were doing it for a living then it is important that you set a rate that earns you what you need to make a decent living. As you are not then it doesn't really matter what you set it at.
And don't worry about the professionals, it is up to them to look after themselves. If they can't make a living selling pens because amateurs are undercutting them then that can do what all turners do and diversify into the much more profitable fields of writing books and magazine articles, demonstrating and selling things to other woodturners. Very few woodturners make a living from only turning these days.
Edit: And I also agree with Neil's comments.
