None of mine are for sale, as we have them scattered around the country to increase tech2 coverage for the club.
Purely for Omegas, all you need is:
Tech2 with VCI module
32Mb (linear, NOT ATA!) PCMCIA memory cards << these are pretty unreliable, and bloody expensive
Cable from VCI to car adapter
OBDII car adapter
TIS of some description (TIS2000 good enough for Omegas)
TIS dongle or valid dealer subscription to GlobalTIS for certain functions like programming
A CANdi interface is essential if you want to do Astra-H, Corsa-D, Vectra-C/Signum, Zafira-B. Tech2 cannot do current Vauxhalls such as Astra, Insignia, Corsa etc, that needs GM MDI. MDI has a software Tech2 capability, so if you have interest in later cars, worth researching further in case MDI is better option.
Not sure if the chinese clones use linear 32Mb cards, or the far cheaper ATA ones (and the Tech2 modified for that, as the genuine interface can't handle ATA).
As for Omega coverage, Tech2 can do everything on all Omegas except a few bits - basically ECUs that were already retired when Tech2 replaced Tech1 in 1997:
U25DT engine ECUs (DDE2.0), as fitted to 2.5TD from 94 to 95
IR immobiliser/locking, as fitted to 94/95 cars
I know at least one member here uses a chinese clone, but I'm not sure if its only for code reads, or if he uses to its full potential.
Do you have much experience with Tech2?