In 2005, 300 euros was a very good price for an unused Writers Edition Friedrich Schiller fountain pen. Collectors regarded a resale at around 450 euros as realistic, and over the counter the model was hard to find below 475 euros; that figure was seen at the time as something of a price floor for Writers Editions in the shops, at least on the Vienna market. With a margin like that the purchase was worth making even if you only meant to sell the pen on again — and if you happen to like it as well, so much the better.
As for where to buy: Montblanc keeps prices fixed in its own boutiques, and Writers Editions were officially not supplied to ordinary stationers. Where such shops or jewellers offered them nonetheless, the stock had come through other channels, and prices there tended to be above rather than below the original list price. Offers well under the usual level are therefore isolated cases and not the rule. Before buying, check condition and completeness: with limited editions the box, inserts and papers are part of the value.