California Catalytic converters

[Shteets]

Well, my daughters Nissan Fontier needs a catalytic converter on bank 2. The Nissan dealers want anywhere from $650.00 - $800.00 for the cat alone. I called all over and no one sold an aftermarket brand of cat for Nissan. I found one on line for under $300.00 and is approved in 49 states. Of course California is one of two states that wont accept the cat and they will not ship it to California.

My question is, is there a difference between the catalytic converters or is it just one of the many tax scams or stupid rules in California to not allow these after market cats into the state?

Are they actually different or the same Cat?
Will it perform equal to a cat purchased at Nissan and meet California emission thresholds?

Any input would be appreciated.

Thanks