Value of Sapphire Engagement Ring

No idea.  The grades of the diamonds and sapphire will make the price.  Judging from what you paid, this should be a really nice piece.  Is there a lab report or appraisal with the ring ?

Nice that you got it back - does not happen often.
 
It is impossible to say what it is worth. Sapphire prices can vary substantially. The price you paid may not be the best indicator of what it is/was worth as some stores can have substantial markups.

As mentioned - did you get an independent (not from Jeweler) appraisal or lab certificate with the ring?  I would suggestion you have a professional appraise/evaluate it in your area. Check the main part of this board for a list of independent appraisers in your area. This will help you understand its value and provide some "backup" to someone else who might by it.

Also if you do a little searching here on PS you will find posts about selling jewelry - here is one very informative post

I would like to suggest that you could use such a nice sized sapphire in some sort of other piece of jewelry for a future lady – but some gals might not like to know that their pendant necklace is based on gems from the ex’s engagement ring!