Escape From Stalag VIIIB
In 1943, one Reichsmark was equivalent to 40 cents.
In comparative terms, it has the same buying power as around $6 or a fiver for Brits. So it should get you a reasonable meal in a cheap diner.
Rationing in Germany by 1943 was even more restrictive than in Britain as virtually everything was rationed there – even bread. Only vegetables were ration free.
As in the UK, there was a black market where items could be bought with the right contacts at prices substantially higher than market rates.