ID

Have an offer to buy a pistol with the markings S/42, which I have found on this site but I am unable to find the identification for the markings on the right side that say,

"La Plata 9mm GER. Number is 8157 with what looks like a tiny "81" but it is probably a small gothic letter.

Any help?

Pistol is in good condition, no magazine, black grips, any rough guess on value?

Thanks, andy.