PSA Graded Card Prices API

import requests
import statistics

API_KEY = "tca_your_key_here"
BASE    = "https://thecardapi.com/api/v1/market"

def grade_premium(card: str, grader: str = "PSA") -> dict:
    """Compare median prices across grades for a card."""
    results = {}
    for grade in ["10", "9", "8"]:
        r = requests.get(
            f"{BASE}/sales",
            params={"q": f"{card} {grader} {grade}", "limit": 50},
            headers={"x-market-api-key": API_KEY},
        )
        r.raise_for_status()
        prices = [s["sale_price"] for s in r.json()["data"]]
        results[f"{grader} {grade}"] = {
            "count":  len(prices),
            "median": statistics.median(prices) if prices else None,
        }

    # Calculate premiums
    grades = [f"{grader} {g}" for g in ["10", "9", "8"]]
    for i in range(len(grades) - 1):
        hi = results[grades[i]]["median"] or 0
        lo = results[grades[i + 1]]["median"] or 0
        if lo:
            results[f"{grades[i]} / {grades[i+1]} premium"] = f"{(hi/lo - 1)*100:.0f}%"

    return results

premium = grade_premium("Mike Trout 2011 Topps Update Rookie")
for label, data in premium.items():
    print(f"{label}: {data}")