I had to check from google to get some idea, so maybe a bit off:
In Finland 100LL is now around 2.2Eur/l thats about 3.1USD one LITRE !
.50 BMG was tough one, apparently its not widely sold because only a small group of sniper rifle enthusiastics shoot .50, so mainly only bullets for reloading purposes are sold in stores.
But i found indications that a shop sold round costs around 10-13 Eur a pop, that translates to around 14-18USD a pop.