Hi falo,
They look quite good, according to the English pages they are laser cut beech wood and vivak (clear thermoforming polyester).
According to my figures the U 35 comes out at about 90cm and the UB III about 77cm, with a price of €382.75 for the UB III, with interior (no crew) I don't feel they are outrageously expensive compared to buying a type VIIC or type IXC and adding the CMK interior. Don't know how accurate they are, not done any research on WW1 boats other than a morbid fascination with the British K Class and the later M class.
Regards
Jon