First of all, the place to learn about suppressors and to ask questions of suppressor owners is
www.silencertests.com Not to take anything away from this board, but that board is all about this one subject.
Ok, $500-$600 seems kind of low. I paid that for the suppressor alone (AAC Evo-9 was like $550). One thing to keep in mind about buying suppressors: they are just like buying anything else. You don't need to pay retail price to get one. And you don't need to pay state sales tax to get one. There are companies that sell suppressors at prices substantually (sp) below retail. You buy the suppressor from them and have it shipped to your local FFL. Speaking only from my personal experience, I paid $550 for the can, $350 for the barrel, something like $80 for the sights, $200 for the stamp.
Barrels: There are several ways you can go with this. If you go with a compact version of your gun, you can buy a barrel from the full sized version and have it threaded. For example, lets say you want to suppress a Glock 17. You could buy a factory Glock 34 barrel, which would stick out past the slide, and have it threaded. I think you mentioned that there is a 5" target model of the gun you want to suppress. You could buy that barrel and have it threaded. Another way to go is to buy an aftermarket barrel. BarSto was suggested; they make very high quality barrels but this would almost certainly be the most expensive possible route to take. I suppressed a Glock 34 and bought the threaded barrel from BarSto. The barrel alone (with a thread protector) was something like $350 and I had to wait for over six months to get the barrel. Go to
www.silencertests.com and see where those guys are getting their barrels. There are actually some companies that make standard production threaded barrels. You might get lucky and find one for your gun.
Suppressors: The first thing you have to know when buying a suppressor for an autoloading handgun is: does the barrel tilt or is the barrel fixed ? I am not familiar with your gun. Examples of barrels that tilt are 1911, Browning HiPower, Glock. Fixed barrel would be something like a Berretta or a Makarov. This determines whether or not you need a recoil booster. If your pistol is fixed barreled, you can not use a suppressor with a recoil booster. If your pistol barrel tilts, you have to have a recoil booster for the action to cycle. I have been told that if you buy a suppressor like the AAC Evo-9 that you can buy a part that replaces the booster allowing you to use it on guns with fixed barrels: I don't know. I personally would just buy a suppressor that works on your gun. In many of these threads people (most of whom don't own suppressors) try to envision senarios where they can buy one suppressor and then adapt it to all their guns. This usually isn't practical. Just buy the right suppressor for your gun and be done with it.
Last long time: Most modern suppressors will last your lifetime if you are an average shooter. Maybe if you are shooting 5000 rounds a week for years on full auto or something, but if you are shooting a normal amount, the suppressor will last forever.
Sights: Yes, the suppressor usually completely blocks the sights. So, if you plan on using sights you need to figure that one out. I have no interest in owning a gun without sights so, on my Glock 34, I bought a set of sights right from AAC that he sells to use with a suppressor. I have heard that Meprolite adjustable sights will allow you to see over the suppressor. This usually isn't that big of a deal to find sights that you can use, but it is an additional expense.
So how does it work ?
I own a suppressed .22 LR handgun (Ruger Mk.II). My AAC Evolution 9 on my Glock 34, using 147 grain bullets at just over 1000 fps is almost as quiet as the .22. It is very impressive. It sounds more like some kind of release of pressurized air: I have heard it described like the sound of disconnecting an air hose from an air tool.