I'm certified in both. Here are some tidbits. With SSI you must be associated with a SSI shop (and thus no independent teaching as you can with PADI). As Skooter said above, talk to the shop owner as they wield significant leverage in deciding costs. Generally though you can work a deal of about half the normal instructor package costs. You'll have to buy all the SSI books, slates, etc (similar costs to PADI). Your PADI instructor knowledge will make it very easy to get through the cert program. Expect similar skills requirements and knowledge requirements. Basically you will sit through the entire SSI instructor class with other candidates. It is very similar to PADI in format. Note, not all SSI shops have an instructor training program. You are not obligated to stay with a particular shop that you do the training with. For insurance, I use iMS. They allow for loss payee to both organizations (I'm assuming you want to stay certified with both agencies). You may have to foot the bill yourself though as the SSI shop is not going to want to pay for the extra cost of both orgs on the insurance. My current yearly bill is $515 (which is not much more than typical PADI instructor liability). You will need to discuss your dual relationship with the SSI shop as the manager may be concerned about conflict of interest (you stealing students for your private PADI teaching). Be aware there is a difference between SSI AOW and PADI AOW. SSI doesn't have a tight relationship with a CPR/FA training org so you'll want to keep current on whatever you have now. As always look for a shop with a pool on premise as it makes the logistics much easier. Let me know if you have more questions.
