Occasionally, a gun has some attributes that are similar to a home. Sometimes, you can put more into remodeling and adding to your home until it is worth more than you can sell it for. I have known people who have done this. But, in one case, they didn't care if they had more in the home than they could sell it for because they did not plan to ever move. Their idea was that they would stay there for the rest of their lives so selling it was not part of the equation. A gun can be like that. If you think you will ever be interested in selling it, do not put more into it than you can ever sell it for. On the other hand, if that gun is a part of your permanent collection then it makes no difference what you spend on it to get it the way you want it and they way that makes you happy.