I know a local brick-and-mortar would be preferable, but if you don't turn up any leads, here's how I finally got the goods to make the Brooklyn: I bit the bullet and ordered Torani Amer from liquorama.net. Shipping for 1 bottle was $13.95 (eek!), and 4 bottles was $18.95 ($4.75 a bottle...that sounds a
little better), so I bought a few other things that either sounded good (relatively inexpensive wine with good ratings) or were harder to find where I'm currently living in NJ (Matusalem rum), finding the shipping easier to stomach that way.