Rash vest in general, both water sports and martial arts.
I can currently get them, but the sizing is Asian....eg I am a large normally, in these XL is a bit small, and they aren't particularly good value.
I have found these folks, they will supply plain rash vests. Haven't asked about price yet....so may yet be a no go.
http://www.mikeclairetextiles.co.uk/rash-vests.asp
As I have other projects on the go, I am not rushing!