For 100 pieces just do it yourself by and with a plumbers torch. Stick the neck in the flame and roll it with your fingers at the base, then drop it in water. If you are burning your fingers you're are heating it too long. I have done thousands of cases this way over the years, never a problem . Btw I do have a giraud annealer and still do small runs by hand my machine is not set up for that caliber.
Akajun method will work for one time small runs. I'd put a stripe of 750 degree Tempilaq inside the case neck. When the stripe changes color the brass has hit the correct temperature.
Although I probably could justify a Giraud annealer I went a more ghetto route.
http://www.cartridgeanneal.com/home.html
Yes you can burn yourself. Yes it's takes a bit of fiddling to get it set up so the flames are in the correct position. But it works and is affordable.
Why do you need to anneal them? Sounds like they are new. If you polish annealed brass the color change disappears. Sometimes not entirely but it is fairly undetectable.I'm going to need 100x Nosler 30-06 Brass annealed.