I agree on the lump sum, which is what I offer. Itemized but not broken down.
"The open water certification costs xxxxxx. This includes manual, 4 classroom sessions, 5 pool sessions, 6 open water dives, gear and tanks for these dives. Certification only requires 4 dives so if I feel you are done in 4, you get two free dives, so long as it is within 2 weeks of being certified. You will have to get yourself to the resort and feed yourself once there. Schedule is very flexible, can be combined or split up, so we should sit down and plan it. It could take 4 days or 3 weeks. Up to you"
"The open water certification costs xxxxxx. This includes manual, 4 classroom sessions, 5 pool sessions, 6 open water dives, gear and tanks for these dives. Certification only requires 4 dives so if I feel you are done in 4, you get two free dives, so long as it is within 2 weeks of being certified. You will have to get yourself to the resort and feed yourself once there. Schedule is very flexible, can be combined or split up, so we should sit down and plan it. It could take 4 days or 3 weeks. Up to you"