If you find rust in the wheel-wells, arches, trunk-pockets, floors, sills & rockers, consider walking away.
If the rust is limited to the trunk floor, and you have a garage or covered space to store it, (To defer doing the window gaskets for now) I'd try to get it for around $2.5K or less. Having owned one of these with the automatic, I consider the 4-speed manual to be very desireable in a car like this.

Happy Motoring, Mark

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DrDKW