Hi,
It's true that there is only a US, Canada and UK versions of the
application, but that doesn't mean that you can't use it outside of those
countries.
In fact I'm using it since 2006 version in Portugal. Of course there are
some limitations, but it depends on what you intended to use it for.
In my case I use it to control debts to control sells and buys. I use it to
create orders and invoices, and to control payments of my clients.
I've an accountant that makes all my accountability, so it is just to
control my bank accounts.
"How to buy" was your question... well I think you can do it on the
internet. In my case, and because I a software developer, I've a MSDN
subscription that includes it.
