Those ones you posted are new to me. The last time I looked was several months ago and there was one or two people selling the bulbs for $30 each or so IIRC. One member made his own but had a separate 12V transformer to power it. I think he may have hid the transformer in the case.
The Singer machines take the bayonet mount bulbs but most Japanese machines I've seen take screw in types.
Rodney

The one you saw with the transformer might have been based on a Necchi. Some of them use 12V auto bulbs and use a transformer.

Cari