My 13-month old doesn't like any of the "boxed" milk substitutes, but
he likes some of the fresh cold soy and rice milk products out there, such
as Silk (soy, but they also make a rice which I haven't tried), the
new soy/nut drink from Odwalla (can't remember the name), and the flavored
rice/nut milks in the Odwalla section (sorry, again no name).  I prefer
these myself, as they taste really fresh and are incredibly tasty.

However, you really don't "need" milk, and it doesn't sound like your
child has much of a milk habit established.  If you are still breastfeeding,
he should be getting his calcium etc there.

K