Digital Multiplication, Subtraction, Division Integrated Circuits?
I think there is some misconception in the question. To get something subtracted-added or multiplied, one has to feed operands, and store result, in some form. So a stand-alone ALU by itself is meaningless unless one builds the infrastructure and sequencers to perform these functions. Which is called "processor", or "CPU". And this "infrastructure" is usually much bigger and more complicated than the ALU itself. So yes, building an ALU alone is not worth it.

In the past, before the ability to build LSI - Large Scale Integrated circuits, there was a technology called "bit-slice", see Wikipedia article. Some remnants like SN74181 (by Texas Instruments) still can be found on e-Bay in vintage section, and probably few other chips from the Wikipedia list.

Today one can easily implement any kind of ALU using small FPGA, and even build full processors around.