1. Used Good Condition: A complete set of World Book Encyclopedias from 1988 in good condition, with all volumes present and no significant damage, can range in value from approximately $100 to $300.
2. Used Very Good Condition: If the set is in very good condition, with minimal signs of wear and tear, the market value can be slightly higher, ranging from around $150 to $350.
3. Used Excellent Condition: A complete set in excellent condition, showing little to no wear, discoloration, or damage, may be valued between $200 and $400.
4. Rare or Special Editions: If your set includes rare or special editions, such as a deluxe or collector's edition, the value may be higher. Collectors may be willing to pay a premium for these editions.
5. Vintage Value: While the 1988 set may not be considered "antique," it does retain some vintage value due to its age. This can add to its appeal for some collectors.
6. Regional Variations: The market value can also vary depending on the region and the demand for encyclopedias in your area.
7. Online Marketplaces: Prices can be more competitive on online marketplaces like eBay or Amazon, where you can find sellers offering the complete set at different price points.
Remember, these values are just estimates, and actual prices realized may differ based on specific market conditions and individual buyers. It's recommended to check reputable online sources or consult with collectors and experts for a more precise valuation.