Maybe try asking here for a local to collect and ship to you?
I can think of several reasons why it isn't popular, based on the standard green form, having both planted and lived with it long-established as hedging.
It is extremely spiny with long and robust spines, it is fussy about soil - forget it on acid soils as it will sulk, it suckers like a mad thing.
So far as growth rate of the green form, it isn't fantastically fast-growing, despite being a hedging plant - the attraction in that role will probably be the spines.