https://www.ducatiforum.co.uk/threads/possibly-the-lightest-899-in-the-country-for-sale.55360/page-3 No idea if it's still for sale
Normally a couple on eBay.... have been quite a few 899’s since they added 959’s. Tend to go for around £7k to £10k+. Just watch out, because some are nothing more than a standard bike without any road gear where the good bits were lifted for the next project or to sell separately. Some though, are still fully specc’d (@Nelson seemed to get a good one). So just make sure you don’t just go for the cheapest....