Try e-gunparts.com, Shotgun News, Gun List, local gun shows, gun shops, etc.
From Bersa. Contact them through their website. Their magazines can be ordered on line from Bersa.
35-90 USD
Depends on the condition,make,model and year.
25 USD
If you mean a 22LR, 200or so
22LR ammunition made to match specifications.
No published sn data
100-1000 USD or so depending on specifics
I have it as the 15 round magazine that fits my model 700 .22lr rifle I bought from Big 5.
$50-$300, depending on exact model and condition.
50 USD to felony jail time depending on specifics
The P-38 in 22LR is the only 22LR pistol made by Walther that looks like a P38
Everything from a scratch to death