In the long run, you'd save yourself money by just purchasing the pricier lavender silkies from a breeder than trying to breed your own from silkie/cochin or orpington crosses. That's generations worth of chickens you'll need to house, feed, and provide care for (or sell/rehome) just to get to the chicken you actually want many years later. Many breeders will ship chicks also, so location may not be an issue.
Now chocolate silkies are harder to come across in the states. If your heart is set on chocolate, if you're unable to find a breeder, and you're willing and able to go the mile to breed for them, then by all means go for it! Just keep in mind that there is two types of chocolate: sex-linked and dun. Sex-linked chocolate iirc is recessive and can be found in Orpingtons, Wyandottes, and Seramas in the states. Dun I think is more common and works like the blue gene, so you would be breeding black/dun/khaki instead of black/blue/splash.
You'll also need to decide if them meeting standard is important because you're going to have to deal with breeding out the nonstandardized traits. Crossing a silke with an orpington, for example, will leave you with issues with:
single combs
reduction of fibromelanism
improper toe number
reduced or missing crests, muff/beard, and foot feathering
red ears
brown eggs
body size conformation
Plus silkie feathering is a recessive trait, and requires frequent back crossing to not lose completely, much like the sex-linked chocolate color itself.
A lot to think about! Sorry for the huge infodump!