Go on eBay and see what the parts are going for. Use 'completed listings'. It's a good source for parts prices in the market 'realtime'. As far as the 'WIN' column; Do your best to talk him down and it will be a win. You only get one chance for that and it's NOW. It's a fine line but try to make freinds with him at the same time as talking him down 'realistically'. If he doesn't like you the deal will never be good.