I don't make a semi bolt, but I sell MPA's semi bolt assembly. The semi bolt shown above is current production & is likely to be available for a long time. Spares are available. Price is $90.00 for a semi bolt assembly, $100.00 shipped.
My bolts are slowfire smg bolts:
They are available as:
Slow Fire ready fixed firing pin bolt assembly, not shown, parkerized, drilled & tapped w/o oprod & ejector assembly, but ready to run in stock M11/9 smg but easily upgraded by end user, $180.00(edit: price typo)
Parked Slow Fire fixed firing pin bolt aseembly, ready to run in prepaired M11/9 smg receiver, as shown above, $200.00.
Armoloyed Slow Fire fixed firing pin bolt assembly, same as above but bolt body chromium impregnated to give surface hardness of 78Rc, $220.00.
My machined steel smg sears are available Armoloyed as well as parked.