In Spain at least, it's more common to use the -ra form ('si fuera rico, me compraría un velero'), but you can use the -se form as well, because it doesn't sound strange at all ('si fuese rico, me compraría un velero').

Very nice. Thank you Ed! I don't think I ever actually learned these in school (or forgot them) so I am trying to learn them now. I've read the se forms and that has confused me, so again ... ¡Gracias!