You can make a shelving unit from 1x4 x 8 foot wood boards. Very inexpensive abpnd then you paint or as in my case, I stained them. Less screws go into the walls whereas the metal shelves need to be screwed into each unless you mount them on a vertical board that willaccess the studs.
Being a car mechanic like you, I have faith in you Chris to do what I describe. If you are interested, I can tell you how I built mine.