A677-Royal Mail “A Celebration of Anniversaries” First Day Cover 11 April 1989

Title:
Royal Mail “A Celebration of Anniversaries” First Day Cover – 11 April 1989 (GB)
Category:
Collectables → Stamps → Great Britain → First Day Covers
Condition:
Good used condition. Envelope shows some corner/tip wear and slight discolouration at one corner (see photos). Stamps affixed and cancelled “First Day of Issue 11 April 1989”. Addressed.
Item specifics:
Year of Issue: 1989
Issuer: Royal Mail (Great Britain)
Cover Type: First Day Cover (FDC)
Theme / Subject: Anniversaries / Postal Telegraph & Telephone / Inter-Parliamentary Union / Public Education / European Parliament
Addressed or Un-addressed: Addressed
Condition Description: Good; minor wear & slight corner foxing/discolouration.
Cancel: “First Day of Issue 11 April 1989” (District letter cancel)
Quantity: 1 cover
Valuation / Recommendation:
Based on comparable listings of UK first day covers from the late 1980s, values are modest (for example one online listing of a 1989 cover at ~£14.50).  Another listing shows a 1989 FDC offered for £4.99.  Therefore for your cover, assuming the cancellations are correct and condition is as described, a fair market valuation would be in the region of £10–£20.
Given the wear and addressed nature, I would recommend listing around £15 as a “Buy It Now” price.
Recommended eBay listing price:
Buy It Now: £15
You might also consider a slight premium (e.g., £18) if the condition is better than typical and you include shipping internationally.
Auction option:
Start Price: £5