Friend's dad has an old 2 section (8' overall) spike tooth harrow laying in a pine thicket. What's a fair price for it? I know I'm not giving a good description but he sent me a pic that didn't show much, just rusty pipe covered in pine straw. He put a $500 tag on it but I said "no thanks". He came back and said to make an offer but I really don't know what to say.