Voultar just posted a video that recommends a $100 (approx) soldering kit that performs as good or better than most equipment many times more expensive. It’s a great walkthrough of both what’s better about it, as well as why it’s better.
EDIT: It’s been reported that not every T12 has the same circuitry as the one Voultar reviewed. I’ve found these links to be very safe and since it’s Amazon shipping is extremely fast.
Keeping your iron’s tip clean is equally as important as the iron itself. Here’s the two tip cleaners I use:
My favorite: https://amzn.to/2AkSgVr
Still good, but doesn’t last as long: https://amzn.to/2UtkLHk
More tips on inexpensive modding tools can be found here: http://retrorgb.com/tools.html