Fairbow produce staves and have them in a selection of woods and prices I am sure they can help you out.
Fairbow's website
They also run workshops on the making of the bow - I know I attended the last one.
If you start with the stave a little longer than you need use self nocks and then move to horn nocks when the bow is nearing completion.
Apparently horn nocks make a longbow - according to
GNAS.