Coste itself is for someone who lives near or on a hillside (cf côte in modern french)
"De" means, most of the time, "originated from"
So my guess would be that "De Coste" means "from hillside" or "from Coste" (a place with 'Coste' name, also meaning ultimately hillside)
Louis de La Coste was born in 1675.
Louis de La Coste died in 1750.
Jacques Coste has written: 'Essais de parachutes dans la grande soufflerie sonique de Modane-Avrieux ..' -- subject(s): Parachutes, Testing
Hippolyte Coste has written: 'Flore descriptive et illustre e de la France, de la Corse et des contre es limitrophes'
This definition is lacking an etymology or has an incomplete etymology
Alexandre Coste's birth name is Alexandre Eric Stphane Coste.
Christian Coste has written: 'Guide de l'assainissement en milieu urbain et rural' -- subject(s): Sanitary engineering, Sewage disposal, Water quality management
Carlos Coste was born in 1976.
Gérard Coste was born in 1939.
Jorge Coste was born in 1988.
Georges Coste was born in 1944.
Charles Coste was born in 1924.