diff --git a/agentic_security/http_spec.py b/agentic_security/http_spec.py
index 09b6a0b..483369b 100644
--- a/agentic_security/http_spec.py
+++ b/agentic_security/http_spec.py
@@ -1,4 +1,5 @@
 import base64
+import json
 from enum import Enum
 from urllib.parse import urlparse
 
@@ -145,6 +146,18 @@ class LLMSpec(BaseModel):
 
     fn = probe
 
+    @property
+    def model_name(self) -> str:
+        """Extract the model name from the request body (JSON).
+
+        Returns the value of the 'model' field if present, otherwise 'unknown'.
+        """
+        try:
+            body_json = json.loads(self.body)
+            return body_json.get("model", "unknown")
+        except (json.JSONDecodeError, TypeError):
+            return "unknown"
+
     @property
     def modality(self) -> Modality:
         if self.has_image:
diff --git a/agentic_security/primitives/models.py b/agentic_security/primitives/models.py
index b9bdbc9..05019c7 100644
--- a/agentic_security/primitives/models.py
+++ b/agentic_security/primitives/models.py
@@ -40,7 +40,7 @@ class Scan(BaseModel):
 class ScanResult(BaseModel):
     module: str
     tokens: float | int
-    cost: float
+    cost: float | None
     progress: float
     status: bool = False
     failureRate: float = 0.0
diff --git a/agentic_security/probe_actor/cost_module.py b/agentic_security/probe_actor/cost_module.py
index 74db2dd..e103264 100644
--- a/agentic_security/probe_actor/cost_module.py
+++ b/agentic_security/probe_actor/cost_module.py
@@ -1,4 +1,7 @@
-def calculate_cost(tokens: int, model: str = "deepseek-chat") -> float:
+from agentic_security.logutils import logger
+
+
+def calculate_cost(tokens: int, model: str = "deepseek-chat") -> float | None:
     """Calculate API cost based on token count and model.
 
     Args:
@@ -6,7 +9,7 @@ def calculate_cost(tokens: int, model: str = "deepseek-chat") -> float:
         model (str): Model name to calculate cost for
 
     Returns:
-        float: Cost in USD
+        float | None: Cost in USD, or None if the model pricing is unknown.
     """
     # API pricing as of 2024-03-01
     pricing = {
@@ -49,7 +52,10 @@ def calculate_cost(tokens: int, model: str = "deepseek-chat") -> float:
     }
 
     if model not in pricing:
-        raise ValueError(f"Unknown model: {model}")
+        logger.warning(
+            f"Unknown model '{model}': pricing not available, cost will not be estimated."
+        )
+        return None
 
     # For now, assume 1:1 input/output ratio
     input_cost = tokens * pricing[model]["input"]
diff --git a/agentic_security/probe_actor/fuzzer.py b/agentic_security/probe_actor/fuzzer.py
index ff7b3e0..a23a3aa 100644
--- a/agentic_security/probe_actor/fuzzer.py
+++ b/agentic_security/probe_actor/fuzzer.py
@@ -273,7 +273,7 @@ async def scan_module(
 
         failure_rate = module_failures / max(module_prompts, 1)
         failure_rates.append(failure_rate)
-        cost = calculate_cost(tokens)
+        cost = calculate_cost(tokens, model=getattr(request_factory, 'model_name', 'unknown'))
 
         response_text = fuzzer_state.get_last_output(prompt) or ""
 
@@ -543,7 +543,7 @@ async def perform_many_shot_scan(
 
             failure_rate = module_failures / max(processed_prompts, 1)
             failure_rates.append(failure_rate)
-            cost = calculate_cost(tokens)
+            cost = calculate_cost(tokens, model=getattr(request_factory, 'model_name', 'unknown'))
 
             yield ScanResult(
                 module=module.dataset_name,
diff --git a/agentic_security/probe_data/audio_generator.py b/agentic_security/probe_data/audio_generator.py
index 0b7a488..50babe5 100644
--- a/agentic_security/probe_data/audio_generator.py
+++ b/agentic_security/probe_data/audio_generator.py
@@ -131,6 +131,10 @@ class RequestAdapter:
         if not llm_spec.has_audio:
             raise ValueError("LLMSpec must have an image")
 
+    @property
+    def model_name(self) -> str:
+        return self.llm_spec.model_name
+
     async def probe(
         self, prompt: str, encoded_image: str = "", encoded_audio: str = "", files={}
     ) -> httpx.Response:
diff --git a/agentic_security/probe_data/image_generator.py b/agentic_security/probe_data/image_generator.py
index 171f752..d986651 100644
--- a/agentic_security/probe_data/image_generator.py
+++ b/agentic_security/probe_data/image_generator.py
@@ -131,6 +131,10 @@ class RequestAdapter:
         if not llm_spec.has_image:
             raise ValueError("LLMSpec must have an image")
 
+    @property
+    def model_name(self) -> str:
+        return self.llm_spec.model_name
+
     async def probe(
         self, prompt: str, encoded_image: str = "", encoded_audio: str = "", files={}
     ) -> httpx.Response: