Price on Celestial Daggers is very variable to be honest.
I paid 25k for my q9 15^50 (non insc) and you should be able to sell for that without much fuss (even more to buyer who wants them).
Trouble is Celestial Daggers are rather small and are not as keenly sought after as say Demon Fangs, Steel Daggers, Storms and suchlike, so at times they can be hard to shift (hence the wide disparity in pricing). I have seen perfect 15^50 offered for as little as 10k all the way up to 60k, however personally the 25k I paid was what I consider to be fair, and my view on that hasn't changed.
If you salvage some mods, sure put them on, but any Sin wanting them will mod how they like in any case, so not a deal breaker.