The concrete that goes into making a sink like the one in the photo should be over 10,000 psi, closer to 14,000+ psi ( 1000 psi = 6.89 MPa ).
The micro toppings come premixed in bags or buckets. Often you just add water. This would be the easier way to do things.
You would still need polishing
Not all concrete is created equal. A quality shop with a good mix design would be in the $2800 to $3800 range for a sink that was approximately 5' x 2' x 6".
Several things can affect cost.
If you still need a sink, have questions, or need a referral feel free to contact me.
concrete counter tops for kitchen and bath
Concrete is a growing segment of the countertop market as well. In the hands of a skilled craftsman, there is practically no shape, color or finish it can't transform into.