There are some available that are advertised in Nuts and Volts magazine, but these are sold in a hobbiest market and are relatively expensive for a product. I would check them out and contact the manufacturer to see what they could do price-wise at your volumes.

geekEE; I think you are screwed... I have looked longingly at serial LCDs for years.. Heck, before just about any job I check.  It always seems to be an absurd over-charge for that feature.  The problem is that LCDs are mass produced in China and re-marketed here, but as soon as serial shows up someone here feels they deserve a fortune for it, so the price is always prohibitive.  They tend to be for hobbyists or pros doing one-offs who can avoid the design hassle of the parallel interface by spending some up front for the serial.

If you find one that is only 10% more let us know.

These are good people but they have the same price issues.
http://www.crystalfontz.com/products/index-ser.html

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

Keith has it pegged
even guys like www.elabinc.com seem to want a pretty penny
for their (guessing) pre burnt micros
Roll your own or find some of the open source code available.
D