A serious valuation requires the writing instrument in hand, since condition is decisive and prices fluctuate strongly with supply and demand. A practical method is to research on eBay via the advanced search: enter the model as precisely as possible (e.g. "Montblanc 136"), search ended auctions worldwide, and narrow further by categories such as Collectibles or Watches & Jewellery if needed. Collector shows in Cologne and Hamburg as well as specialist forums (fountainpen.de, penexchange.de, fountainpennetwork.com) are further sales channels, although prices achieved there are clearly below eBay levels because collectors usually only buy at bargain prices and have a high level of price knowledge. Selling at shows also incurs stand fees.