I like the suggestions cwilkson & andrewb provided. Including your suggestion for 'A notification system for machines for sale (or wanted)'
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A 'For Trade' option with the ability to select a list of games you'll trade for.
Listing how far 'traders' are willing to drive far for a trade. Some sellers are willing to drive far for a sale (rare, but it happens). Listing how far buyers are willing to drive for a purchase.
Under the section where you would list a distance/mileage: Instead of listing a mileage number, you can simply click and option of 'Anywhere' or 'Depends', which would just be default maximum distance.
List the ZIP or Town/City of the game for sale/trade. Sometime the game location is different than the sellers profile location.
The ability for the people to set the distance units of measure. Either KM or MI.
The list of 'Games your willing to Trade' is separate from your 'want list'. You might have a Centipede on your want list. But you may not be willing to trade your Williams Turkey Shoot for one.
I did forget to add (in the pictures below) how people like to do
partial trades. So I would incorporate that as well.
Example:
Your Game <-> (Game you Want + 'X*' USD) *Default is '0'
Turkey Shoot <-> (Centipede + $2000)
or if default for 'X' is '0'
Turkey Shoot <-> Centipede
Took a lot of elements from Pinside, which seems to be working well for them?
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______ For Sale & For Trade_____
______Trade Only _____
______ Selling Only _____
______ Wanted _____

Under 'Want To Buy': 'Condition' is just where you type the description of what youre looking for. This feature is already present.