It is what it is - a promotional marketing item. Look for similar displays on eBay, Craigslist & Kijiji to get an an idea. The Shaq sized shoe, is it an OG pair or a retro? Are both left and right shoes present?
Bear in mind that it's a Reebok item so the demand is not as high as Nike but with some patience and a reasonable asking price you'll be able to move it.