Proof is a certain type of strike, resulting in cleaner detail and a shinier finish. Mint condition refers to regular strike coins, but that haven't been used or spent.
For 2017: in uncirculated condition, about $24. in Proof condition, about $60.
All Australian 1992 coins are potentially still in circulation so, unless they are a Proof or Uncirculated mint set or are individual Proof or Uncirculated coins and in absolute mint condition, they are worth whatever is inscribed on them.
Assuming the coin's denomination is given in euro cents and not pence, you have a common circulation coin from Ireland. In that case it's not worth any premium. Ireland is part of the eurozone so a euro coin would not have entered circulation any earlier than 2002. If it's not a euro coin, please post a new and separate question with its date.
Isle of Man coins follow the dimensions, metallic composition and history of the equivalent British coins. The Half New Penny and Half Penny coins, the larger pre-1994 5 and 10 Pence coins and the larger pre-1997 50 Pence coins have been withdrawn. Unless they are part of a Proof or Uncirculated mint set or are individual Proof or Uncirculated coins and in absolute mint condition, they have little or no value. All other coins are still potentially in circulation so, unless they are part of a Proof or Uncirculated mint set or are individual Proof or Uncirculated coins and in absolute mint condition, they are worth whatever is inscribed on them.
These coins have only just been released into circulation so, unless they are part of a Proof or Uncirculated mint set or are individual Proof or Uncirculated coins and in absolute mint condition, they are worth 50 cents. If you have a Proof coin or an Uncirculated mint condition coin, they are worth whatever you just paid for them.
These coins are no longer in circulation since they were withdrawn and demonetised in 1987. Unless they are part of a Proof or Uncirculated mint set or are individual Proof or Uncirculated coins and in absolute mint condition, they have little or no value.
These coins are no longer in circulation since they were withdrawn and demonetised in 1987. Unless they are part of a Proof or Uncirculated mint set or are individual Proof or Uncirculated coins and in absolute mint condition, they have little or no value.
These coins are no longer in circulation since Irelands changeover to the Euro in 2002. Unless they are part of a Proof or Uncirculated mint set or are individual Proof or Uncirculated coins and in absolute mint condition, they have little or no value.
These coins are potentially still in circulation so, unless they are part of a Proof or Uncirculated mint set or are individual Proof or Uncirculated coins and in absolute mint condition, they are worth 2 cents.
These coins are no longer in circulation since Irelands changeover to the Euro in 2002. Unless they are part of a Proof or Uncirculated mint set or are individual Proof or Uncirculated coins and in absolute mint condition, they have little or no value.
These coins are still potentially in circulation so, unless they are part of a Proof or Uncirculated mint set or are individual Proof or Uncirculated coins and in absolute mint condition, they are worth 50 Pence.
These coins are no longer in circulation since Irelands changeover to the Euro in 2002. Unless they are part of a Proof or Uncirculated mint set or are individual Proof or Uncirculated coins and in absolute mint condition, they have little or no value.