I travelled in Mexico once upon a time. The seller of any product would inflate the cost of something 4x it's value so if an inexperienced gringo talked him down to half the asking price, he would be ahead. Guess who the inexperienced on was?
Based on that experience, and knowing the condition is poor, starting at less than half for the pair is not out of line. And if he is not ok with it, he should counter offer. I would not worry about offending him. Unless he is stupid.
I've just given away hundreds if dollars of stuff because I needed to in a short timeframe. The value of the space it was in was higher than the cost, so I ate it and parted. Unless you know his motivation, start low. $1000-1250 would be my opener, for what it's worth.