For best pricing, check the internet stores, Sailnet, APS, PYacht, Boaters World (on-line), etc. A few months ago I purchased an Icom M3 for $135 which included shipping, and the regular stores sell it for $149 plus tax (or 160). I bought this unit over other similar units because it had a dual use battery tray (includes rechargeable Ni-Cads, but can use AA's if the charge goes out.) It is not a submersible unit and will need a pouch if you are sailing a small cat.
The prices of other units run from $90 to over $300, depending upon features. Some of the newer models have Lithium batteries. More expensive, but they are advertised to hold a charge much longer and for the batteries to last longer.