Well, after looking at several Seat Belt Cutters, I decided they probably couldn't adequately handle aircraft webbing. Specifically, the $5 pieces of plastic I found had a small razor embedded in them that would probably work great for thin automobile seat belts, but not aircraft seat belts. So, I decided to take the advice posted earlier about folding knives and went with the following:
Rescue Junior Folding Knife - $49
To answer some of the recent PM's concerning "where" I purchased the components listed above, please see the following websites:
Concorde Aerosales
Malcolm Murray
Kriana
Pocket Lights
Amazon
Sure Fire
Spyderco
By the way, Malcolm Murray is an older gentleman and kind of a technology neophite (doesn't take credit cards). However, he was very pleasant to talk to and will offer more advice on signal mirrors than you probably wanted to know! You should shop around, I bought the Spyderco from Amazon because they had a pretty good sale.
Concerning GPS compatibility with PLB's (using the NMEA 0183 optical standard), I couldn't find a list of Garmin
Submersible GPS units that reflect their most recent product line. The E-trex is compatible (and cheap), but it isn't submersible - only waterproof. I just sent a request to Garmin for an updated list, and will post their reply when I get one. For compatibility, you must have an NMEA 0183 output ready GPS unit and a GPS interface cable. The NMEA 0183 optical interface connector supplied with your PLB must be connected to the GPS interface cable. Some GPS units require you to program "header" or "message" information to meet the proper format (codes).
(edited to update URL)