Hey, subject test fee for GRE Subject Test is independent from the choice of subject.

Fees for GRE Subject Test:
Subject Tests — worldwide $150

Special Handling Requests Price
Late registration fee (online registration only) $25
Standby testing $50
Rescheduling fee $50
Changing your test center $50
Changing your Subject Test $50

Psychology Subject Test Content includes:

EXPERIMENTAL SUBSCORE — 40%
Learning (3–5%)
Classical Conditioning
Instrumental Conditioning
Observational Learning, Modeling
Theories, Applications and Issues
Language (3–4%)
Units (phonemes, morphemes, phrases)
Syntax
Meaning
Speech Perception and Processing
Reading Processes
Verbal and Nonverbal Communication
Bilingualism
Theories, Applications and Issues
Memory (7–9%)
Working Memory
Long-term Memory
Types of Memory
Memory Systems and Processes
Theories, Applications and Issues
Thinking (4–6%)
Representation (Categorization, Imagery, Schemas, Scripts)
Problem Solving
Judgment and Decision-making Processes
Planning, Metacognition
Intelligence
Theories, Applications and Issues
Sensation and Perception (5–7%)
Psychophysics, Signal Detection
Attention
Perceptual Organization
Vision
Audition
Gustation
Olfaction
Somatosenses
Vestibular and Kinesthetic Senses
Theories, Applications and Issues
Physiological/Behavioral Neuroscience (12–14%)
Neurons
Sensory Structures and Processes
Motor Structures and Functions
Central Structures and Processes
Motivation, Arousal, Emotion
Cognitive Neuroscience
Neuromodulators and Drugs
Hormonal Factors
Comparative and Ethology
States of Consciousness
Theories, Applications and Issues

II. SOCIAL SUBSCORE — 43%
Clinical and Abnormal (12–14%)
Stress, Conflict, Coping
Diagnostic Systems
Assessment
Causes and Development of Disorders
Neurophysiological Factors
Treatment of Disorders
Epidemiology
Prevention
Health Psychology
Culture and Gender Issues
Theories, Applications and Issues
Lifespan Development (Childhood, Adolescence, Aging) (12–14%)
Nature-Nurture
Physical and Motor
Perception and Cognition
Language
Intelligence
Social and Personality
Emotion
Socialization, Family and Cultural Influences
Theories, Applications and Issues
Personality (3–5%)
Theories
Structure
Assessment
Personality and Behavior
Applications and Issues
Social (12–14%)
Social Perception, Cognition, Attribution, Beliefs
Attitudes and Behavior
Social Comparison, Self
Emotion, Affect and Motivation
Conformity, Influence and Persuasion
Interpersonal Attraction and Close Relationships
Group and Intergroup Processes
Cultural and Gender Influences
Evolutionary Psychology, Altruism and Aggression
Theories, Applications and Issues

III. OTHER AREAS — 17%
General (4–6%)
History
Industrial-Organizational
Educational
Measurement and Methodology (11–13%)
Psychometrics, Test Construction, Reliability, Validity
Research Designs
Statistical Procedures
Scientific Method and the Evaluation of Evidence
Ethics and Legal Issues
Analysis and Interpretation of Findings