I'm still working on the concept but I'm not making much progress. But I do have goals, sort of.
I may have mentioned already what I'm looking for in a new pistol and it may have changed since I posted that. Aside from the cost (always a consideration) of the basic pistol, there is the cost of replacing all the accessories you generally accumulate for a particular gun. Things like holsters, magazine pouches, spare magazines and sometimes even spare parts. If you foolish pick a different caliber, there's the element of both building up a stock of the new caliber and disposing of the old, but my present stock is one of the limiting factors in deciding, not that it is much of a limitation. I mean, I have plenty of 9mm, .45 ACP and .38 Special. What else is there?
Ultimately, the thing that probably holds me back the most at the moment is the fact that any new gun is only going to be a marginal improvement (if any) over what I already have. I already have pretty much decided that it ought to work the same way, although that was as much a result of elimination as anything else. In other words, once you eliminate all the things you can't afford in the first place, then choosing from what you can becomes a little easier. In the meantime, you continually experiment and investigate other options, most of which come to nothing for any of a number of reasons.
The hardest element, frankly, is keeping the practical aspects in front. I am, admittedly, a gun nut and the simple novelty of many guns is attractive and sometimes irresistable. I will also admit to being swayed somewhat by the last movie I happened to watch, which could even have been made in 1947, after which I have a strong desire to own another Colt Police Positive Special, never carried in a holster, just thrust in a pocket. But I doubt anyone else here is ever influenced by the movies.