$10 is fine if it is a small job, say 200 grafts (postage stamp jobs).
There has to be a minimum fee in there somewhere to cover the malpractice insurance, and the opportunity cost of missing out on a larger job.
However above 1,000 grafts you'd expect it to be on a sliding scale.
I've had FUE quotes ranging from $8.75 (1,000 grafts) down to $6 for the larger jobs (for grafts above 2,000).