Sometimes it has nothing to do with level. I have two characters. First is guns and sneak, second is a melee cannibal. My first guy could never find reinforced leather anywhere, but had no trouble finding metal and reinforced metal. I didn't want either for him. The second guy finds reinforced leather everywhere, but metal of any kind is extremely rare. First guy cannot find a scope for Trail Carbine or Brushgun (30th level), Second guy has no trouble finding them (18th level), but can't find the melee weapons he wants. First guy also has no probs finding mods for EW, but that is probably because he doesn't use them. Seems the game is rigged to give you what you don't need or want.
:rofl: I've had games like that.
However I know the exact placement of all none unique weapon both spawns and lootable ones.
So shopping is a lot easier, but mods I still have trouble with.