I kinda see both sides point, me personally if I was selling my car for 15,000 or trade, I wouldn't put the trade value higher. If someone had a trade I liked and thought was fair I would trade. If they where asking 15,000 for their car and I didn't think it was worth it I wouldn't trade. If they where asking 13,000 for their car and I thought it was a good trade so be it, I would trade.