I will make a few suggestions to you
You can Purchase a Ruger II for example and put anatomical grips on them (i.e. adjustable one).
Here are some links to grip makers - a grip will cost between $125-225 CDN.
http://www.marschalgrips.com/index.php?content=Match_grips-models
http://www.formgriffe.de/english/
Currently internationally Walther are still used, but the Pardini 22lr is King. The Russian IZH is very popular as well. Check out Targetshooting.ca - they have a firearms database (you are looking at a STD pistol)
Hammerli's are not common as Hammerli's SP20 has had problems
Matchguns MG2 - great pistol but has suffered from quality control problem
The Morini CM22 is not common, but used. You need a small or Medium size hand to use it.
The quality of a Walther GSP Expert is not the same as the GSP make 15 years ago. I would not be scared to buy a used GSP as they are built like tanks!
A really good value Standard Pistol is the MCM, aka Margolin. For a plinking gun than you can compete with its a great value.
If you let me know where you live I can try to put you in touch with someone locally to let you try some guns.
Brian