DumaLove has it completely correct, you should not think of breeding to recoup your investment, if you are going to think that way then factor in all the additional expenses. IF you want to do it right you have a lot of testing but you also may face emergency vet bills (not all pregnancies go smoothly) and you might need to nurse kittens around the clock and sadly you may lose some. We often miss that in the wild, most kittens don't make it.It's not always the joy of kittens but the heartbreak of a baby not making it.
Add to that, if you are thinking you are going to use unregisted males with your cat, you are going to be creating outcrossed mixed breed kittens, whereby it is going to be difficult to even get some of that money you are thinking you will get to pay yourself back for this cat. Did you pay for breeding rights? If not, you are producing unregistered kittens hence even less saleable.
You may mistake kittens that are nonstandard colors with those "part Siamese" with kittens that have the recessive and nonstandard colorpoint gene, which is actually a very different thing. The colorpoint gene (the one responsible for the Siamese type coloring but does not mean the breed) is recessive and may pop out in Savannahs but that doesn't make the kitten outcrossed, it still has papers. Black Savannahs actually are permissible as the Serval itself comes in a black form, this is the result of the nonagouti (solid) gene, also recessive. BUT do not mistake those genes with unplanned breedings like using domestic shorthaired cats in a program. By using your mixed breed male kittens you will simply be producing more mixed breed kittens, not terribly saleable ones.
I am glad that you are discussing this here, it really is good to think through what you are doing. It may seem a simple thing to just breed your expensive SV kitten... the reality is that it may not be the easy money you might think. Even those of us that have bred SVs for some years, we didn't rightly know how darn difficult it would be at first. I wish there had been a forum like this to help me when I started. Really do read and learn and listen before taking that step!