If I understand this correctly, the same ips you refer to are actually different ips (192.168.0.2, 192.168.0.3, etc.), but using the same subnet (255.255.255.0), whereas what you want is different subnet ips (192.168.0.2, 192.168.1.2, etc.), each with different default gateways?

If that's what you want, the cheapest way maybe to use an old pc with a linux os (ipcop for eg) and multiple nics. That'll do the job.

TEk