I love beautiful ceramic floors but IMO, a ceramic shop floor is not a good idea.
Ceramic is expensive, labor intensive to lay, cold, hard and breaks.
There are large rubber and plastic mats used to cover garage floors that I think would be better on a shop floor.
These large mats or tiles will make a quieter, warmer floor and much more forgiving when something is dropped. Moisture should not hurt this type of tile. Also much easier to install.
A lot of ceramic is slick. This rubber flooring is not.
If you don't have time to do it right the first time, when will you have time to do it over?