If you will permit my guess rather than any insider or industry information, two things came to my mind upon reading your question. One, Aulos doesn’t sell bad instruments; and Two, when you make any musical instrument, the smaller the method generating pitch, the more out-of-tune and significant any amount of error becomes. That was a tough sentence to write as I was a music major rather than a physics major. But if you use a Guitar string as an example, if a fret is misplaced in the fingerboard by an equal 1 mm at both the 1st fret and 15th fret locations, the 15th fret’s pitch will sound far more out of tune (than the 1st fret’s) because 1 mm is a much higher percent of error at the shorter vibrating string length way up at that 15th fret. Conversely, 1mm has far less impact on intonation down at the 1st fret with its much longer vibrating length of string. I hope that makes sense.
Too wordy as all that sounds, I’d imagine that the precision and (I’d suspect) pitch-correction labor needed after the initial molding pushes the cost of production up a bit.
Remember, the Aulos Garklein (501S) is a one piece instrument. You cannot tune it yourself. And I can’t help but think about how much smaller Aulos’s marketplace is for the Garklein.
I’ve accumulated many, many plastic recorders over the 65-ish years since my first in Grade School. Most of those are Aulos. I’ve never had an intonation problem. Cost compared to a wooden instrument? I’m thinking the little Aulos Garklein is a good deal if your musical journey gets you to it. I’d be kind of worried about the intonation of any recorder priced by the inch – No?