second strobe

I have a Olympus OMD EM5 Mark II in an Olympus housing and one Sea & Sea YS D1 Strobe. I am looking to add a second strobe. They discontinued the YS D1 and I don't really want to spend the $700 for a YS D2J. Is there another strobe that I can buy that will work well with my set up? The YS 01...