Poor you. I am afraid that I can't help on the toy front, but I can heartily recommend the book 'Tatty Ratty' which might pave the way to a slightly different bunny being accepted. It's a very charming story.
We recently had to retrace our steps around a v large shopping centre looking for DD's comforter. Eventually left our details with their lost property office and they called that evening to say someone had handed it in.
So I read your post with much sympathy and did a few searches - there's a pic of the same one on someone's blog with a link to Ethical SUperstore but they don't seem to stock them anymore, but maybe worth contacting them re suppliers as bumbling suggests?
Was thinking about the suppliers, but reckoned by the time we'd travelled that route, we'd be over the worst. Searched all over the web to no avail. Local shops were lovely and did a full search. Honestly, we had him outside furthest shop on the parade, and he was gone by the time we got home, 200m away, having stopped at one other shop. Went back immediately but didn't find him.
I think another child must have picked it up, hence the posters.
Am kicking myself as he never normally leaves the cot.