Hi Carlo,
It is getting quite hard these days to find expansions for the CD32 and CDTV. The CD32 had the SX-1, SX32, and ProModule for RAM expansion and extra ports, but you'll find it impossible to find one of these new anywhere, and sellers of second hand units seem to know how much demand there is for them and don't generally sell them cheap. You can however still buy brand new floppy disk drives for the CD32 that plug into the expansion port, and also provide additional parallel/printer port (useful for hooking up a sound sampler, video digitiser or Parnet network cable) and has a Real-Time Clock in it, so your CD32 will always know the time and date, handy for when you're saving files to floppy and want to sort by time/date.
You can get them brand new here:
http://cgi.ebay.co.uk/Floppy-Drive-for-Amiga-CD32-Games-Console_W0QQitemZ360224428322QQcmdZViewItemQQptZUK_VintageComputing_RL?hash=item53df0c9122
