In the 200-300 range your looking at bottom of the line basic models with little to no differentiation capabilities between different metals.
These have a shallower range and can't really distinquish well between say a bottle cap, a coin or a chunk of iron. And they won't usually pick up the faint signals like a gold chain.
If you want to do coin shooting or look for jewelry or gold, you need at least a Fisher Gold bug II or Teknetics G2 or equivalent but they are in the 700-800 range
I have the Teknetics G2 that I bought new for $700, and it works really well