Hello,
I agree that selling the lock with the key is better than just the key. However, selling the entire safe just might be better. When you say that it weighs a lot, keep in mind, some of us move safes for a living. So weight is sometimes not that big of an issue.
If you want several points of view on the “value” of your safe, post photos of it here. This web site is viewed by the top collectors in the world, so I’m quite sure one of us will give you an educated point of view as to value.
Just as a side note, one of those keys has been on ebay now for quite some time, it is still there because it is over priced. At a recent lock auction good examples of that key sold for $20. Over the years, I’ve purchased entire safe locks with keys for around $100.
Please post photos….who knows, you just might have a one of a kind, and don’t know it.