You are so right! Silly me, and good to know.
Here's the page where you can read about it (Google translated). Some figures don't translate very well - the span clearly should be 150 cm (not inches), and the length ca 75 cm.
Note that you will need some ten meters of 2x2 mm balsa stringers (which can be cut from one 2mm sheet of balsa, as suggested in the text).
I see the price is 179 zloty, and I'll take your word for it that this will translate into the 50+ euros you mention.
Thank you for finding out about this, and making this important correction! Now we have in fact made a real ontribution to this thread. The SZD-15 "Sroka" is alive and well as a most beautiful paper model of a glider, at an impressive scale.
Here's a little bit about the original (Google-translated good Polish site).
Apparently, the name "Sroka" translates into Magpie - not a too flattering name for what seems to have been an excellent glider in its own time.
We should also note that the Magpie is available as one in the series of GPM 1:33 scale glider models mentioned earlier in this thread, No. 9, 2004.
Here's a very detailed build report at a Polish site.
Pretty model, isn't it? From a model-building point of view an attractive fact is the canopy, which doesn't require shaping into compound curves. The gliders in this series are actually quite detailed, a fact which you will appreciate if you follow the thread (
Google-translated here).
I believe the registration no., "1957", to be fictitious, referring to the year of its first flight.
Leif