It should be pretty straightforward to buy the parts through dealers here on CPF or a couple well respected sites.
Here's a list I made for another thread, be aware there are other, usually cheaper options- different reflectors, battery adapters, battery options, etc.
These are the ones I'd choose though.
Also andrewwynn sells the
'hotdriver', a circuit he made to regulate voltage for hotwire bulbs like the 1185.
It prevents the normal voltage spike during powerup from reaching the bulb, apparently extending bulb life significantly. He sells an assembled version with a Kiu socket, so there's no need to mess with the mag switch yourself. I don't own one yet, but I'm planning on buying one for my next hotwire build.