EVERYONE LOVES A BARGAIN
I'm no different than you, and sometimes there are some real deals on used equipment. However, do your homework and know the where the snags can be.
Take a VHF radio as an example.
Buying a used VHF radio or an automatic identification system, or AIS, unit? Beware. If you buy used equipment with a maritime mobile service identity (MMSI) number already logged into it, you may not be able to track down the previous owner in charge of the MMSI to get it reassigned to you. The MMSI goes with the boat. In an emergency, your equipment may be sending out a distress call with someone else's information. Rescuers will be looking for a different boat and will be calling the previous owner of the equipment to verify an emergency.
The process of clearing the old MMSI and having it reassigned to your control may even require shipping the equipment to the manufacturer to be reset. Before you buy a flea market VHF, make sure you can contact the previous owner