The 406's (which I suppose one could define as "digital") have been available for quite some time and certainly are not new (as such). Currently 406's start at about $1600 and go up from there depending.
The 121.5/243's (which could be classed as "anologue") currently cost around the $200-$230 #mark and fit the requirements as far as regulations go.
BUT
Satellite detection of 121.5/243 will be terminated (that's already been announced) so these will basically become obsolete towards 2006/9 when that side of the system is terminated. 2006 I believe is the termination date for the Russian satellites and about 2008/9 for the American sats.
406's have it all over 121.5's as far as safety goes and also don't have the problems that the 121.5 system has suffered from. Hopefully as the time approaches 406 prices will drop otherwise there may certainly be some issues.
#
Cheers, Kerry.