how can I profit the most with 1 single product?...

Buzz over to Clickbank. Check out the "learn guitar" products there, and see what others are doing to extend their products. That may give you some ideas on how to beef up your own line. Once you have some sales going on, a JV with a guitar store could be a nice upsell. Especially if you could offer a little discount.

- Nightowl

If you have your product in a digital format as well as on a CD, why not start by offering it as a digital download on your sales letter.

Then you could create an instant upsell by offering a "Deluxe" version which will be the physical CD/DVD.

You could filfill the physical orders with Kunaki.com which allows you to do low cost fulfillment to anywhere in the world.

Physical products often have a higher perceived value so you could make the deluxe version higher priced, and ensure you also allow for the cost of shipping.

Once you've done this, think about developing your own product line for this niche - like someone else said above, have a look on Clickbank and other sites and see what others are selling.

Also survey your list as soon as you have a good sample size (500+) and find out what kind of products or training they really want, so you can ensure you have a built in customer base for any new product you develop

Hope this helps - most importantly just get your first product online and start promoting it asap.

~James Dyson