I wish; As far as I know if you want a topre spacebar you either buy a new keyboard or a full keycap set.
Well, the way I see it, we don't buy all Cherry MX caps from Cherry. Several people seem to make caps just fine...
Can anyone with an already-established connection with someone like Signature Plastics ask them if they can replicate a standard, ABS, single-shot unprinted Topre space bar if provided with a sample? Lots of people seem to run group buys here which result in keys from SP - perhaps one of these people would be kind enough to ask?