I purchased a non-working K58 a few months ago and rebuilt it (read cleaned, resealed, and lubed). It is a very accurate airgun with a typically very fine Pardini trigger.
The K58, an SSP (single stroke pnuematic), is ideal for take along shooting and at home shooting in that it requires no support equipment except for pellets. You cock it, place a pellet in the chamber, aim, and shoot (a 10 of course).
Mine shoots at 440 fps using the typical light weight wad cutters (either RWS 10 Lites or Nygord). It will shoot as good as the shooter. In other words, the gun will not hold you back.
K58 drawbacks are really only one: you have to cock it each time you fire. This might not sound like much, but after a 60 shot ISSF type match, your arm will know it. Hence, the reason for the progression to Co2 powered target airguns, and eventually to compressed air powered airguns.
A new K58 will cost $795 from Nygords. That and a few tins of pellets and you are ready to shoot. A used K58 is very difficult to find - I looked for nearly a year. A good one will be priced around $500.
Or, you can buy a reconditioned K60, the Co2 powered sister model to the K58, from Pilkguns for $380. You will have to get a siphon type 20# Co2 tank for bulk refill at an estimated cost of $100 (available nearly any place). A single fill of a #20 Co2 tank (about $10) will last for 50,000 shots or more - but, who's counting anyway.
Pilkguns also has a number of used PCP (compressed air) target pistols shown on their site starting at $900. Along with a PCP air pistol, you will need a scuba tank and yoke - figure on about $300 for the tank and yoke.
I stopped at Co2. I am happy with my K60 air pistol and shoot 50 to 100 shots daily. I also like my K58, which is set up with a red-dot site and used for non-ISSF type shooting. Each has their place. You might also want to look at the Russian made IZH-46M SSP air pistol. It probably represents the most bang for the buck in today's target air pistol market.
If you would like to learn more about airguns in general, take a look at
www.airguninfo.com - which will have answers to most of your questions (and probably keep you busy for a couple of evenings just reading what's there).
I read and looked for six months before I went for an air pistol - but it sure is nice to be able to shoot at home, rather than driving miles to the range in the middle of the winter. Well, that's probably more than you wanted to read - but, perhaps I managed to answer your questions or create some more questions.