Unconvinced of the need for transmit, other than for social interest of where ur mates are etc. You have one of the most movable, versatile boats ever designed. Pretty much most boats with AIS will be less manouverable, so I'd just avoid them. But I can see rare uses in things like fog but would be concerned that I can only see big stuff like ships who at least should have a horn rather than a tidly yacht who should but hasnt .
There is a Chinese company who clearly make a bit of kit for one of the big players in commercial stuff and have cloned it. Its not CE marked. Tut Tut.
For receive only any risk from no CE would be yours for Tx I guess there would be a small risk you wipe out the whole frequency and prevent two big ships seeing each other and they have a ding...
Here's a thread elsewhere about them: