The first option would be to find a research group that has published with it and ask them to send you some.  It costs them nothing to divert a few ul of a miniprep, so people usually help. 

Second, if you know the sequence, you can always have it made from scratch by a gene synthesis company.  If you need to synthesize replication control regions, like an origin, alert them to it in the comments, as it can interfere with their production.