I'd say GSG1911. I guess I can't say for sure it isn't ammo picky, because all I've ever run through mine is the cheap Wally World Federal 550 packs and it eats those just fine. I think others have said that the CCI ammo works fine in them as well.
Browning Buckmark. There are lots of choices. Suggest you at least try to hold several and hopefully be able to shoot before making your purchase. I did none of that and got lucky with the Buckmark.
All I can tell you, is DO NOT buy a Chiappa 22lr pistol.
They also go by the name Puma. They are bad and I mean
bad, pistols.
I am turning mine in at the next gun buy back, and taking my lumps.
If you prefer a semi auto there are many as has been mentioned already. I would also recommend a Beretta Neos. My LGS has them in 4" and 6" models for about $269, well within your budget and good shooters.
Your great great great grandkids will someday be shooting it. I have a Ruger MK I that I bought when I first turned legal. Countless rounds through it. And it still shoots like as champ. My kids shoot it now...and someday my grandkids will.
I like my Ruger Mark I. My Dad was a huge Ruger fan - he had both a Mark I and a Single Six (as well as several others). I don't think you could go wrong with either of those.
I've had very good luck with Ruger .22cal. revolvers and pistols. Myself I prefer adjustable sights. I've never had any experiance with the model 22/45's but figure they would be great plinkers also. At least 95% of my
shooting I use Federal bulk pack ammunition and next to no problems
with it. I have a Ruger standard I bought back in the 60's and no telling how many rounds thru it and still works like a new one.
ive got one of the newer walther p22s and a heritage roughrider 22 that are both great fun accurate little guns walther can be had for aroudn 250 to 300 and the heritage for about 150 also got a ruger sp101 in 22 but its a little over the 400 dollar price range