Act as a seasoned sports memorabilia investor with over 15 years of experience in the industry. Provide a comprehensive guide on the best ways to invest in sports memorabilia, covering key strategies for [beginners/intermediate/advanced] collectors. Include insights on how to identify [high-value items/underrated gems] and avoid common pitfalls like [counterfeits/market bubbles]. Discuss the importance of [authentication/provenance] and how to leverage [auctions/private sales/online platforms] for optimal returns. Tailor your advice to a budget range of [$500-$5,000/$5,000-$50,000/$50,000+] and highlight trends in [specific sports/eras/athletes] that are currently undervalued or poised for growth. Offer actionable tips for building a diversified portfolio and maximizing long-term appreciation.