This well-rated Spa Sensations 7.5" High Bi-Fold Box Spring drops in price from $94 to $75 for Twin, $149 to $115 for Full, $129 to $104 for Queen, and $199 to $165 for King at Walmart.com. Plus, shipping is free or you can elect free store pickup, if available in your area. This is the best price we could find based on similar products. The fabric-and-steel box spring compresses for mobility and storage. It also comes with a one-year limited warranty. Sales tax is charged in most states.