2-3 years ago, 200 rounds of Port was going for about $40, I have seen South African in 140 rounds battle packs going for $60 and up (2 years ago it was $30). I would figure at least double what you paid for it.
It is a free market, nobody HAS to buy it, you saved it and now can benefit from what is today a pretty rare commodity. I wouldn't feel a bit guilty asking between $70 to $80 for it myself if it were mine. Maybe $70 because it has to be de-linked.
But that is me....I am an evil capitalist.