Old post but I wanted to fix a few misconceptions. I have an F7 Savannah in the UK, and her breeder keeps F1 upwards so I got to hang out with a bunch of them.
Money wise it really varies, I had mine as a retired queen so cost was very little, less than one of my moggies. Kittens as pets are not unreasonable at later generations. Kittens for breeding get into the thousands easily.
Health wise they have no issues but all cats should be tested for common conditions before breeding. My cat is tested for PK deficiency.
As far as breeding, Bengals were involved in some early programs but that's generally frowned upon now due to confirmation and temperament issues. Almost all breedings are Savannah to Savannah of various generations or Savanah to Serval. So you can use an F1 Savannah girl (SavannahxServal) and breed directly back to a Serval for a more Serval like offspring. In this way later generations are looking more and more like Servals.