Ah, a noble cause! As new components there is well over a thousand pounds worth of parts there, as a rough guide. However as I mentioned, secondhand they are worth much less. The reason is simply that while all vehicle manufacturers have to comply with exhaust emissions and noise levels, many owners of bikes like Harleys like to make their bikes noisier. The simplest way to do that is to remove the factory stuff and replace with aftermarket components, for which there is a big market and wide choice. A common source of similar secondhand exhausts is the UK Ebay website, where complete exhaust systems similar to yours are advertised between £150 and £600 pounds. What they actually sell for isn't certain, without following a few for a while. I can't improve on 14GuineaPig's suggestion above for the model it came off. Hope that helps - and good luck with selling it!