if you just want to listen, maybe just buy a scanner?
if its just a marine hand held you want, cobra do a neat little one for about £65
if you want top quality look at Icom hand helds (from £100 plus)
or rolls royce quality - buy a Sailor - (400 quid!)
I you just want something that works, I've got a couple in the shed that are missing battery packs (standard horizon one IIRC but could be wrong) perfect working order, you could just clip a 12v supply on to the terminals.