Congratulations on your first Heuer!

I can't see the photos in your post, but value is never easy.

The 13-1 although not that common is not one of the most sought after watches, so doesn't command the premium you see with other Heuer watches. Another factor is the PVD case and possible wear which makes values vary significantly.

The reference 12 and 13-1 have been considered a good entry level into Heuers and sit somewhere at the higher end of the 1000 series divers and a bit under the Lemania movement Heuers in terms of values. It just so happens I'm looking at a 13-1 at this moment, not for the first time but with specific reasoning this time.