From (potentially faulty) memory, there are some resin kits of sub scasers. There may be an ancient Lindberg SC, with potentially limited accuracy, and unicorn availability.
There are plans available of at least a couple of the ones given a "class." They are nice simple hull forms and would be good scratch build candidates.
Armaments and accessories are available in a number of scales, too.
Dunno. That's the 2¢ I can come up with.