A few years ago I got my first ever Carcassonne for Christmas

. It is the base game in the new artwork. So I played it with my family and we really enjoyed so I decided to go down to my local Mind Games(which has now shutdown

) and buy an expansion. Little did I know the expansion I bought was in the old art (at this point I didn't even know there is 2 art styles). When I got home I was annoyed at the fact I spent money on an expansion that didn't even match

. I didn't like the fact the tiles don't match so I have only used a couple of times.
So my question is how much is a copy of Abbey and Mayor in the old art that I have only used a couple of times worth in USD?
Thanks For Your Help!:)
Note: Mind Games is a Australian Board Game Shop Chain.
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