Spare tire replacement?

The spare tire on my 2000 Insight has a slow leak. I need to pump it up about every week. I have tried to get a replacement tire from two local Honda dealers and a Firestone place, with no luck. The dealer that currently has the car for a battery replacement (more on that later) said they weren't able to order one from Honda and actually called a few junk yards but weren't able to find one. Their only suggestion was that they could get us a full size spare for several hundred dollars which probably wouldn't fit under the cargo area. Firestone tried to order one, but after about a month said they wouldn't be able to get it.

Surely we can't be the only Insight owners who need to replace their spare tire! Any ideas where to get one?