I just had a similar experience at a kindergarten interview and was told exactly the same figure as Zoe.
I say interview - the principle spoke to me (ie. I wasn't given much opportunity to speak) for ten minutes, showed me around the building then told me to wait while they sorted out my contract. CONTRACT? Was I being offered the job? She had said nothing to that effect, only the same kind of "do you think you could do that?" questions I'd had at every other interview.
An HOUR later she called me in to ask if I could I wait longer as "they" still hadn't finished the contract. I wasn't sure what this really meant so I said I could wait but asked if I could take the contract away to look over it. Apparently it had to be signed there so she told me the "terms" and said I could come back tomorrow to sign it. Pay, annual leave etc all sounded reasonable but I was still unsure about this 25K fee. Especially in light of the 3 month notice period. I understand completely that these companies want to avoid teachers coming and going (someone I know compared english teaching in HK to a bar job anywhere else in the world) but to be honest the whole thing just made me feel quite confused and uncomfortable.
I've been for quite a few interviews here now and at most of them I have received really mixed signals. Maybe it's just a different style than I've been used to but often I felt like I had already been offered the job, before they really knew much about me. The woman at this interview didn't seem to need any convincing that I could teach, despite knowing that I have no real experience and little training.
Zenon, your advice is reassuring and this contract did have a 3 month probation period but I just felt like the whole thing was a bit strange.
Bizarrely, I think this might be the only company I've encountered that wouldn't be expecting me to work illegally while my visa was being processed.