The Thunder Tiger Neptune appeared on the model submarine scene a few years ago and made an instant impact with it's ease of construction and the tendency to work straight out of the box! It came in two versions...a kit which the buyer assembled and supplied the radio equipment, or for those who for one reason or another cannot build the kit version, the boat was supplied in a RTG(Ready To Go)version, complete with a six channel radio installed...it was literally a case of 'add water and go'.
Thunder Tiger also offer a 'plug it in an' go' video camera for the Neptune, but the one downfall with this is that it has a umbilical cord used to transmit the video footage back to the monitor, which not only limits the range of the boat, but the cable can get tangled in underwater obstructions if you're not careful.
Since then, the Neptune has proved itself to be a worthy adversary to some of the much more expensive boats, many people have modified their Neptune's to look different, some have installed internal and external lighting, some have onboard wireless video cameras installed, and at least one boat is in the initial stages of having an operating grab arm installed.
Although initially seemingly expensive, the Neptune can work out to be an economical entry into the world of r/c model submarines...buying the RTG version leaves the buyer with nothing else to buy, even the batteries(rechargables)are installed and the chargers are all supplied.
If your modelling space or your expertise is limited, then the Neptune could well be for you.