It is exceedingly common as a garden plant. Surely you will find several within a few mins walk of you, if you live in a residential area. Can't you wander around your locality and ask to take a sucker from someone?

I've even seen it in public plantings, for example outside supermarkets and the like. Could probably steal one from there.

It does come in various varieties. If you want a specific variety for the particular leaf form, etc, you'd be better off buying one from a garden centre, they aren't expensive.

Some do seem to sucker more than others, don't know why.