I use a zinc plater in Denver, the cost for zinc plating every part on a sandcast restoration is under $200.
The result is always excellent, all the parts are plated in one batch. The finished appearance of all the parts is the same and it is not time consuming, plating a few parts at a time. By the time one purchases the equipment and materials to set up for plating, the cost of doing so will match or exceed the cost to have the parts sent out.
The zinc plater I've used, has never lost a single part. When I say every part on a restoration, that includes all the tiny parts, such as the carb parts.
Just my 2 cents worth.