Good defensive ammo these days is constructed and loaded to perform quite well, and to penetrate to similar depths in test media, while being loaded with low-flash powders. In the early 1980's, I would have really wanted to get my hands on a compact all-steel .44 SPL revolver, but today I feel just as well-armed with an SP101 in .357 magnum. While the custom .44 would have a higher cool factor, the SP101 is entirely practical, which being more compact.
Now, for something really special in .44 Special, that is obtainable, take at look at single action sixguns. Or, if DA is vital, keep looking at the larger dealer websites and the online auctions for pre-owned customs by Clements and ASP.