The ornamental design for a golfballretriever, as shown and described.
FIG. 1 is a perspective view of a golf ball retriever showing my new design in association with its environment;
FIG. 2 is a front view thereof;
FIG. 3 is a left side view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a top view thereof;
FIG. 6 is a bottom view thereof; and,
FIG. 7 is a perspective view thereof.
The broken lines shown in FIG. 1 are included for the purpose of illustrating the environment of the golf ball retriever and form no part of the claimed design.