High Current Power Supply Schematic
No, this will not work. It may also kill you.

The SCRs you're looking at are expensive because 1500A is an immense amount of current. Mechanical switches capable of safely switching this current will cost even more, if they exist at all.

Additionally, as noted in comments, the "protection diodes" in your circuit appear to be backwards. Even assuming that this is a mistake, it's unclear what their purpose is, and they would need to be rated for at least 1500A as well if they were included.