I don't see the Simrad/B&G 3G/4G type radars at West Marine website anymore. They seemed safer to be near and less energy hungry. So what was the problem?
Navico still sells the 3g and 4g radar, but the newest and coolest is the Halo. Also based on "broadband" technology, it's not marketed as such anymore because everybody has it, so it's not really a distinguishing feature. The Halo has all of the advantages of the 3/4G and lots more too.
If you are upgrading and can afford it, the Halo is clearly a step up.
You may find (if you want one) a Simrad/B&G/Lowrance (Navico) 3/4G Broadband Radar through a distributor, but as they no longer manufacture them anymore, they are getting very thin on the ground and most distributors no longer have any in stock...
As above I would be looking at the new Halo range.