Hi Martin,
Meade serial numbers give a rough sort of sequence/clue but without any seeming convention. I have read that looking for dates of manufacture on electronics inside give a reasonable date.
You can join the group below (great for LX200 owners) then go to Database/Serial Numbers and you will find a listing of a few hundred LX200s where owners have listed serial numbers, model, purchased dates, delivery condition etc, its a reasonable guide I guess.
I found the following that maybe useful to you, bearing in mind purchased dates don't necessarily account for items in stock at a dealer for periods of time and perhaps overseas delivery.
SN03476 April 2002 UK delivery = EMC (pre GPS model)
SN05509 April 2002 10inch GPS (earliest GPS I can find) USA delivery
SN07822 October 2002 10inch GPS USA delivery
SN08376 December 2002 8inch GPS USA delivery
SN090982 April 2003 USA delivery
SN093611 June 2003 USA
SN093700 January 2004 Scotland
SN094655 March 2003 USA
SN095123 May 2003 USA
SN095560 August 2004 USA
SN095593 January 2005 Europe
SN096171 June 2004 Canada
SN096532 February 2004 Netherlands
SN097084 September 2004 USA
SN100427 December 2005 USA
SN100723 September 2006 USA
SN103097 (My 12inch R 'scope) June 2007
http://tech.groups.yahoo.com/group/LX200GPS/
PeterM.