I just bought a new Geuns/Wakker to replace my W15-Ln. I have been playing it regularly for the past 5 years or so and have been very pleased with it. Contrary to what you might hear, not all Stagi's are alike. Most of the models do have a problem with the key's falling over to one side and bellow's leak's and what not. The W15-ln does not have the hose pieces under the button's that get brittle and come apart as do all other models of Stagi. The only reason I bought the new Geuns/Wakker is because I had the occasion to play a Wheatstone this past summer and realized there were better concertinas, but not at a price I could afford.
If you are sill interested, I would sell my Stagi for $450. It still play's as good as it did when it was new and it has never needed any repair's. If you are interested, call me at 402 527-5197.