Ask a gunsmith for help
100-400 or so
0-400 USD depending on model, age, condition
I don't know how much it varies, but here in Madison WI. there's a Excellent condition 'Slightly Used' Mark II .380 w/ Asking price of $200. If it is the 400 model it will range from $110.00 to $180.00 depending on condition.
Best to ask a gunsmith for help
$400-$500 in excellent condition.
Gun shop, gun show, gunpartscorp website.
380
It is: (400-380)/380 times 100 = 5.263% increase to three decimal places
400.
400 - 20 = 380
Retail value, you'd be looking at the $200 - $400 range, dependent on condition and calibre (9x17/.380 ACP or 9x18 Makarov).