The Bevin Brothers Bell Company of East Hampton, Connecticut, are the
only makers of one-piece cast sleigh bells.  If I remember correctly,
the bells can be had either in sets, affixed to leather straps, or
singly.

Sleigh bells are available in various configurations from:

  Mast Harness Hardware
  115 E  C.R. 500 N
  Arthur IL 61911

  Tel: 217-543-3463

The Mast catalogue seems to have cheap bells and cast bells, but does
not mention the Bevins name.  Masts's bells are specified by diameter,
rather than by tuned note.

I wonder if it's possible to tune sleigh bells with a file, and whether,
historically, anyone has ever though it necessary?  Generally, sleigh
bells are supposed to sound a bit raucous, to provide a warning, because
a sleigh going through unpacked snow is almost completely silent.  The
snow muffles even the sound of the hooves.

Peter Neilson